Номер 31.3, страница 221 - гдз по физике 10-11 класс задачник Гельфгат, Генденштейн

Физика, 10-11 класс Задачник, авторы: Гельфгат Илья Маркович, Генденштейн Лев Элевич, Кирик Леонид Анатольевич, издательство Илекса, Москва, 2008, красного цвета

Авторы: Гельфгат И. М., Генденштейн Л. Э., Кирик Л. А.

Тип: Задачник

Издательство: Илекса

Год издания: 2008 - 2026

Уровень обучения: профильный

Цвет обложки: красный лупа, парень едет на велосипеде

ISBN: 978-5-89237-252-7

Электродинамика. Магнитное поле. 31. Магнитное поле. Вектор магнитной индукции. Упражнения - номер 31.3, страница 221.

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                            "name" => "11"
                            "field_cases" => array:6 [
                              "field_accusative_case" => "одиннадцатый"
                              "field_creative_case" => "одиннадцатым"
                              "field_dative_case" => "одиннадцатому"
                              "field_genitive_case" => "одинадцатого"
                              "field_nominative_case" => "одинадцатый"
                              "field_prepositional_case" => "одиннадцатом"
                            ]
                            "field_translit" => "odinadcatyj"
                          ]
                          #original: array:6 [
                            "id" => 5460
                            "created_at" => "2026-04-10 13:58:26"
                            "updated_at" => null
                            "name" => "11"
                            "field_cases" => array:6 [
                              "field_accusative_case" => "одиннадцатый"
                              "field_creative_case" => "одиннадцатым"
                              "field_dative_case" => "одиннадцатому"
                              "field_genitive_case" => "одинадцатого"
                              "field_nominative_case" => "одинадцатый"
                              "field_prepositional_case" => "одиннадцатом"
                            ]
                            "field_translit" => "odinadcatyj"
                          ]
                          #changes: []
                          #casts: []
                          #classCastCache: []
                          #attributeCastCache: []
                          #dateFormat: null
                          #appends: []
                          #dispatchesEvents: []
                          #observables: []
                          #relations: []
                          #touches: []
                          +timestamps: true
                          +usesUniqueIds: false
                          #hidden: []
                          #visible: []
                          #fillable: []
                          #guarded: array:1 [
                            0 => "*"
                          ]
                        }
                      ]
                      #escapeWhenCastingToString: false
                    }
                    "field_publisher" => Illuminate\Database\Eloquent\Collection {#1167
                      #items: array:1 [
                        0 => App\Models\Term {#1168
                          #connection: "mysql"
                          #table: "terms"
                          #primaryKey: "id"
                          #keyType: "int"
                          +incrementing: false
                          #with: []
                          #withCount: []
                          +preventsLazyLoading: false
                          #perPage: 15
                          +exists: true
                          +wasRecentlyCreated: false
                          #escapeWhenCastingToString: false
                          #attributes: array:6 [
                            "id" => 5158
                            "created_at" => "2026-04-10 13:58:26"
                            "updated_at" => null
                            "name" => "Илекса"
                            "field_cases" => null
                            "field_translit" => "ileksa"
                          ]
                          #original: array:6 [
                            "id" => 5158
                            "created_at" => "2026-04-10 13:58:26"
                            "updated_at" => null
                            "name" => "Илекса"
                            "field_cases" => null
                            "field_translit" => "ileksa"
                          ]
                          #changes: []
                          #casts: []
                          #classCastCache: []
                          #attributeCastCache: []
                          #dateFormat: null
                          #appends: []
                          #dispatchesEvents: []
                          #observables: []
                          #relations: []
                          #touches: []
                          +timestamps: true
                          +usesUniqueIds: false
                          #hidden: []
                          #visible: []
                          #fillable: []
                          #guarded: array:1 [
                            0 => "*"
                          ]
                        }
                      ]
                      #escapeWhenCastingToString: false
                    }
                    "field_author" => Illuminate\Database\Eloquent\Collection {#1169
                      #items: array:3 [
                        0 => App\Models\Term {#1170
                          #connection: "mysql"
                          #table: "terms"
                          #primaryKey: "id"
                          #keyType: "int"
                          +incrementing: false
                          #with: []
                          #withCount: []
                          +preventsLazyLoading: false
                          #perPage: 15
                          +exists: true
                          +wasRecentlyCreated: false
                          #escapeWhenCastingToString: false
                          #attributes: array:12 [
                            "id" => 4102
                            "created_at" => "2026-04-10 13:58:26"
                            "updated_at" => null
                            "name" => "Гельфгат"
                            "field_bio" => null
                            "field_degree_rp" => null
                            "field_foreign_lang_name" => null
                            "field_foreign_lang_patronymic" => null
                            "field_foreign_lang_surname" => null
                            "field_name" => "Илья"
                            "field_patronymic" => "Маркович"
                            "field_surname_rp" => null
                          ]
                          #original: array:12 [
                            "id" => 4102
                            "created_at" => "2026-04-10 13:58:26"
                            "updated_at" => null
                            "name" => "Гельфгат"
                            "field_bio" => null
                            "field_degree_rp" => null
                            "field_foreign_lang_name" => null
                            "field_foreign_lang_patronymic" => null
                            "field_foreign_lang_surname" => null
                            "field_name" => "Илья"
                            "field_patronymic" => "Маркович"
                            "field_surname_rp" => null
                          ]
                          #changes: []
                          #casts: []
                          #classCastCache: []
                          #attributeCastCache: []
                          #dateFormat: null
                          #appends: []
                          #dispatchesEvents: []
                          #observables: []
                          #relations: []
                          #touches: []
                          +timestamps: true
                          +usesUniqueIds: false
                          #hidden: []
                          #visible: []
                          #fillable: []
                          #guarded: array:1 [
                            0 => "*"
                          ]
                        }
                        1 => App\Models\Term {#1171
                          #connection: "mysql"
                          #table: "terms"
                          #primaryKey: "id"
                          #keyType: "int"
                          +incrementing: false
                          #with: []
                          #withCount: []
                          +preventsLazyLoading: false
                          #perPage: 15
                          +exists: true
                          +wasRecentlyCreated: false
                          #escapeWhenCastingToString: false
                          #attributes: array:12 [
                            "id" => 4104
                            "created_at" => "2026-04-10 13:58:26"
                            "updated_at" => null
                            "name" => "Генденштейн"
                            "field_bio" => null
                            "field_degree_rp" => null
                            "field_foreign_lang_name" => null
                            "field_foreign_lang_patronymic" => null
                            "field_foreign_lang_surname" => null
                            "field_name" => "Лев"
                            "field_patronymic" => "Элевич"
                            "field_surname_rp" => "Генденштейна"
                          ]
                          #original: array:12 [
                            "id" => 4104
                            "created_at" => "2026-04-10 13:58:26"
                            "updated_at" => null
                            "name" => "Генденштейн"
                            "field_bio" => null
                            "field_degree_rp" => null
                            "field_foreign_lang_name" => null
                            "field_foreign_lang_patronymic" => null
                            "field_foreign_lang_surname" => null
                            "field_name" => "Лев"
                            "field_patronymic" => "Элевич"
                            "field_surname_rp" => "Генденштейна"
                          ]
                          #changes: []
                          #casts: []
                          #classCastCache: []
                          #attributeCastCache: []
                          #dateFormat: null
                          #appends: []
                          #dispatchesEvents: []
                          #observables: []
                          #relations: []
                          #touches: []
                          +timestamps: true
                          +usesUniqueIds: false
                          #hidden: []
                          #visible: []
                          #fillable: []
                          #guarded: array:1 [
                            0 => "*"
                          ]
                        }
                        2 => App\Models\Term {#1172
                          #connection: "mysql"
                          #table: "terms"
                          #primaryKey: "id"
                          #keyType: "int"
                          +incrementing: false
                          #with: []
                          #withCount: []
                          +preventsLazyLoading: false
                          #perPage: 15
                          +exists: true
                          +wasRecentlyCreated: false
                          #escapeWhenCastingToString: false
                          #attributes: array:12 [
                            "id" => 4583
                            "created_at" => "2026-04-10 13:58:26"
                            "updated_at" => null
                            "name" => "Кирик"
                            "field_bio" => null
                            "field_degree_rp" => null
                            "field_foreign_lang_name" => null
                            "field_foreign_lang_patronymic" => null
                            "field_foreign_lang_surname" => null
                            "field_name" => "Леонид"
                            "field_patronymic" => "Анатольевич"
                            "field_surname_rp" => null
                          ]
                          #original: array:12 [
                            "id" => 4583
                            "created_at" => "2026-04-10 13:58:26"
                            "updated_at" => null
                            "name" => "Кирик"
                            "field_bio" => null
                            "field_degree_rp" => null
                            "field_foreign_lang_name" => null
                            "field_foreign_lang_patronymic" => null
                            "field_foreign_lang_surname" => null
                            "field_name" => "Леонид"
                            "field_patronymic" => "Анатольевич"
                            "field_surname_rp" => null
                          ]
                          #changes: []
                          #casts: []
                          #classCastCache: []
                          #attributeCastCache: []
                          #dateFormat: null
                          #appends: []
                          #dispatchesEvents: []
                          #observables: []
                          #relations: []
                          #touches: []
                          +timestamps: true
                          +usesUniqueIds: false
                          #hidden: []
                          #visible: []
                          #fillable: []
                          #guarded: array:1 [
                            0 => "*"
                          ]
                        }
                      ]
                      #escapeWhenCastingToString: false
                    }
                    "field_author_foreign" => Illuminate\Database\Eloquent\Collection {#1173
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_book_type" => Illuminate\Database\Eloquent\Collection {#1174
                      #items: array:1 [
                        0 => App\Models\Term {#1175
                          #connection: "mysql"
                          #table: "terms"
                          #primaryKey: "id"
                          #keyType: "int"
                          +incrementing: false
                          #with: []
                          #withCount: []
                          +preventsLazyLoading: false
                          #perPage: 15
                          +exists: true
                          +wasRecentlyCreated: false
                          #escapeWhenCastingToString: false
                          #attributes: array:10 [
                            "id" => 6518
                            "created_at" => "2026-04-10 13:58:26"
                            "updated_at" => null
                            "name" => "Задачник"
                            "field_book_type_foreign" => null
                            "field_cases" => array:6 [
                              "field_accusative_case" => "задачник"
                              "field_creative_case" => "задачником"
                              "field_dative_case" => "задачнику"
                              "field_genitive_case" => "задачника"
                              "field_nominative_case" => "задачник"
                              "field_prepositional_case" => "задачнике"
                            ]
                            "field_plural_form" => null
                            "field_short_name" => null
                            "field_short_name_foreign" => null
                            "field_translit" => "zadachnik"
                          ]
                          #original: array:10 [
                            "id" => 6518
                            "created_at" => "2026-04-10 13:58:26"
                            "updated_at" => null
                            "name" => "Задачник"
                            "field_book_type_foreign" => null
                            "field_cases" => array:6 [
                              "field_accusative_case" => "задачник"
                              "field_creative_case" => "задачником"
                              "field_dative_case" => "задачнику"
                              "field_genitive_case" => "задачника"
                              "field_nominative_case" => "задачник"
                              "field_prepositional_case" => "задачнике"
                            ]
                            "field_plural_form" => null
                            "field_short_name" => null
                            "field_short_name_foreign" => null
                            "field_translit" => "zadachnik"
                          ]
                          #changes: []
                          #casts: []
                          #classCastCache: []
                          #attributeCastCache: []
                          #dateFormat: null
                          #appends: []
                          #dispatchesEvents: []
                          #observables: []
                          #relations: []
                          #touches: []
                          +timestamps: true
                          +usesUniqueIds: false
                          #hidden: []
                          #visible: []
                          #fillable: []
                          #guarded: array:1 [
                            0 => "*"
                          ]
                        }
                      ]
                      #escapeWhenCastingToString: false
                    }
                    "field_country" => Illuminate\Database\Eloquent\Collection {#1176
                      #items: array:1 [
                        0 => App\Models\Term {#1177
                          #connection: "mysql"
                          #table: "terms"
                          #primaryKey: "id"
                          #keyType: "int"
                          +incrementing: false
                          #with: []
                          #withCount: []
                          +preventsLazyLoading: false
                          #perPage: 15
                          +exists: true
                          +wasRecentlyCreated: false
                          #escapeWhenCastingToString: false
                          #attributes: array:6 [
                            "id" => 9
                            "created_at" => "2026-04-10 13:58:26"
                            "updated_at" => null
                            "name" => "Россия"
                            "field_cases" => array:6 [
                              "field_accusative_case" => null
                              "field_creative_case" => null
                              "field_dative_case" => null
                              "field_genitive_case" => null
                              "field_nominative_case" => null
                              "field_prepositional_case" => null
                            ]
                            "field_translit" => "rossiya"
                          ]
                          #original: array:6 [
                            "id" => 9
                            "created_at" => "2026-04-10 13:58:26"
                            "updated_at" => null
                            "name" => "Россия"
                            "field_cases" => array:6 [
                              "field_accusative_case" => null
                              "field_creative_case" => null
                              "field_dative_case" => null
                              "field_genitive_case" => null
                              "field_nominative_case" => null
                              "field_prepositional_case" => null
                            ]
                            "field_translit" => "rossiya"
                          ]
                          #changes: []
                          #casts: []
                          #classCastCache: []
                          #attributeCastCache: []
                          #dateFormat: null
                          #appends: []
                          #dispatchesEvents: []
                          #observables: []
                          #relations: []
                          #touches: []
                          +timestamps: true
                          +usesUniqueIds: false
                          #hidden: []
                          #visible: []
                          #fillable: []
                          #guarded: array:1 [
                            0 => "*"
                          ]
                        }
                      ]
                      #escapeWhenCastingToString: false
                    }
                    "field_city" => Illuminate\Database\Eloquent\Collection {#1178
                      #items: array:1 [
                        0 => App\Models\Term {#1179
                          #connection: "mysql"
                          #table: "terms"
                          #primaryKey: "id"
                          #keyType: "int"
                          +incrementing: false
                          #with: []
                          #withCount: []
                          +preventsLazyLoading: false
                          #perPage: 15
                          +exists: true
                          +wasRecentlyCreated: false
                          #escapeWhenCastingToString: false
                          #attributes: array:6 [
                            "id" => 15
                            "created_at" => "2026-04-10 13:58:26"
                            "updated_at" => null
                            "name" => "Москва"
                            "field_cases" => array:6 [
                              "field_accusative_case" => null
                              "field_creative_case" => null
                              "field_dative_case" => null
                              "field_genitive_case" => null
                              "field_nominative_case" => null
                              "field_prepositional_case" => null
                            ]
                            "field_translit" => "moskva"
                          ]
                          #original: array:6 [
                            "id" => 15
                            "created_at" => "2026-04-10 13:58:26"
                            "updated_at" => null
                            "name" => "Москва"
                            "field_cases" => array:6 [
                              "field_accusative_case" => null
                              "field_creative_case" => null
                              "field_dative_case" => null
                              "field_genitive_case" => null
                              "field_nominative_case" => null
                              "field_prepositional_case" => null
                            ]
                            "field_translit" => "moskva"
                          ]
                          #changes: []
                          #casts: []
                          #classCastCache: []
                          #attributeCastCache: []
                          #dateFormat: null
                          #appends: []
                          #dispatchesEvents: []
                          #observables: []
                          #relations: []
                          #touches: []
                          +timestamps: true
                          +usesUniqueIds: false
                          #hidden: []
                          #visible: []
                          #fillable: []
                          #guarded: array:1 [
                            0 => "*"
                          ]
                        }
                      ]
                      #escapeWhenCastingToString: false
                    }
                    "field_series" => Illuminate\Database\Eloquent\Collection {#1180
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_umk" => Illuminate\Database\Eloquent\Collection {#1181
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_level_of_education" => Illuminate\Database\Eloquent\Collection {#1182
                      #items: array:1 [
                        0 => App\Models\Term {#1183
                          #connection: "mysql"
                          #table: "terms"
                          #primaryKey: "id"
                          #keyType: "int"
                          +incrementing: false
                          #with: []
                          #withCount: []
                          +preventsLazyLoading: false
                          #perPage: 15
                          +exists: true
                          +wasRecentlyCreated: false
                          #escapeWhenCastingToString: false
                          #attributes: array:6 [
                            "id" => 40
                            "created_at" => "2026-04-10 13:58:26"
                            "updated_at" => null
                            "name" => "профильный"
                            "field_cases" => array:6 [
                              "field_accusative_case" => "профильный"
                              "field_creative_case" => "профильным"
                              "field_dative_case" => "профильному"
                              "field_genitive_case" => "профильного"
                              "field_nominative_case" => "профильный"
                              "field_prepositional_case" => "профильном"
                            ]
                            "field_translit" => "profilnyy"
                          ]
                          #original: array:6 [
                            "id" => 40
                            "created_at" => "2026-04-10 13:58:26"
                            "updated_at" => null
                            "name" => "профильный"
                            "field_cases" => array:6 [
                              "field_accusative_case" => "профильный"
                              "field_creative_case" => "профильным"
                              "field_dative_case" => "профильному"
                              "field_genitive_case" => "профильного"
                              "field_nominative_case" => "профильный"
                              "field_prepositional_case" => "профильном"
                            ]
                            "field_translit" => "profilnyy"
                          ]
                          #changes: []
                          #casts: []
                          #classCastCache: []
                          #attributeCastCache: []
                          #dateFormat: null
                          #appends: []
                          #dispatchesEvents: []
                          #observables: []
                          #relations: []
                          #touches: []
                          +timestamps: true
                          +usesUniqueIds: false
                          #hidden: []
                          #visible: []
                          #fillable: []
                          #guarded: array:1 [
                            0 => "*"
                          ]
                        }
                      ]
                      #escapeWhenCastingToString: false
                    }
                    "field_standart_of_education" => Illuminate\Database\Eloquent\Collection {#1184
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_publication_number" => null
                    "field_publication_type" => Illuminate\Database\Eloquent\Collection {#1185
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_under_the_edition" => Illuminate\Database\Eloquent\Collection {#1186
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_under_the_edition_degree" => null
                    "field_cover_description" => "лупа, парень едет на велосипеде"
                    "field_publication_year" => "2008"
                    "field_publication_year_until" => null
                    "field_part" => ""
                    "field_part_writing" => ""
                    "field_second_foreign_language" => null
                    "field_for_whom" => "Учебное издание"
                    "field_allowed" => null
                    "field_reserve_field" => null
                    "field_link_to_source" => null
                    "field_tasks_count" => "459"
                    "field_priority" => null
                    "field_default_folder" => "/fizika_10/gelfgat-z/"
                    "field_isbn" => "978-5-89237-252-7"
                    "field_cover" => array:1 [
                      0 => "/media/fizika_10/gelfgat-z/covers/cover1.webp?ts=1756049816"
                    ]
                    "field_cover_alts" => array:1 [
                      0 => ""
                    ]
                    "field_covers" => array:1 [
                      0 => array:4 [
                        "path" => "/media/fizika_10/gelfgat-z/covers/cover1.webp?ts=1756049816"
                        "alt" => ""
                        "width" => "1566"
                        "height" => "2412"
                      ]
                    ]
                    "field_popular_book" => "0"
                    "field_recommended_books" => Illuminate\Database\Eloquent\Collection {#1187
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_new_book" => Illuminate\Database\Eloquent\Collection {#1188
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_old_book" => Illuminate\Database\Eloquent\Collection {#1189
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_url" => "/10-klass/fizika/gelfgat-zadachnik"
                    "field_cover_color" => Illuminate\Database\Eloquent\Collection {#1190
                      #items: array:1 [
                        0 => App\Models\Term {#1191
                          #connection: "mysql"
                          #table: "terms"
                          #primaryKey: "id"
                          #keyType: "int"
                          +incrementing: false
                          #with: []
                          #withCount: []
                          +preventsLazyLoading: false
                          #perPage: 15
                          +exists: true
                          +wasRecentlyCreated: false
                          #escapeWhenCastingToString: false
                          #attributes: array:6 [
                            "id" => 46
                            "created_at" => "2026-04-10 13:58:26"
                            "updated_at" => null
                            "name" => "красный"
                            "field_cases" => array:6 [
                              "field_accusative_case" => "красный"
                              "field_creative_case" => "красным"
                              "field_dative_case" => "красному"
                              "field_genitive_case" => "красного"
                              "field_nominative_case" => "красный"
                              "field_prepositional_case" => "красном"
                            ]
                            "field_translit" => "krasnyy"
                          ]
                          #original: array:6 [
                            "id" => 46
                            "created_at" => "2026-04-10 13:58:26"
                            "updated_at" => null
                            "name" => "красный"
                            "field_cases" => array:6 [
                              "field_accusative_case" => "красный"
                              "field_creative_case" => "красным"
                              "field_dative_case" => "красному"
                              "field_genitive_case" => "красного"
                              "field_nominative_case" => "красный"
                              "field_prepositional_case" => "красном"
                            ]
                            "field_translit" => "krasnyy"
                          ]
                          #changes: []
                          #casts: []
                          #classCastCache: []
                          #attributeCastCache: []
                          #dateFormat: null
                          #appends: []
                          #dispatchesEvents: []
                          #observables: []
                          #relations: []
                          #touches: []
                          +timestamps: true
                          +usesUniqueIds: false
                          #hidden: []
                          #visible: []
                          #fillable: []
                          #guarded: array:1 [
                            0 => "*"
                          ]
                        }
                      ]
                      #escapeWhenCastingToString: false
                    }
                    "field_metatags_title" => null
                    "field_metatags_description" => null
                    "field_h1" => null
                    "field_description_top" => null
                    "field_description_bottom" => null
                    "breadcrumbs" => array:3 [
                      "class" => 381
                      "subject" => 556
                      "class_subject" => 494
                    ]
                  ]
                  #original: array:50 [
                    "id" => 5400
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "field_tree_default_status" => "tasks"
                    "field_pages_status" => null
                    "field_subject" => Illuminate\Database\Eloquent\Collection {#1163}
                    "field_class" => Illuminate\Database\Eloquent\Collection {#1164}
                    "field_publisher" => Illuminate\Database\Eloquent\Collection {#1167}
                    "field_author" => Illuminate\Database\Eloquent\Collection {#1169}
                    "field_author_foreign" => Illuminate\Database\Eloquent\Collection {#1173}
                    "field_book_type" => Illuminate\Database\Eloquent\Collection {#1174}
                    "field_country" => Illuminate\Database\Eloquent\Collection {#1176}
                    "field_city" => Illuminate\Database\Eloquent\Collection {#1178}
                    "field_series" => Illuminate\Database\Eloquent\Collection {#1180}
                    "field_umk" => Illuminate\Database\Eloquent\Collection {#1181}
                    "field_level_of_education" => Illuminate\Database\Eloquent\Collection {#1182}
                    "field_standart_of_education" => Illuminate\Database\Eloquent\Collection {#1184}
                    "field_publication_number" => null
                    "field_publication_type" => Illuminate\Database\Eloquent\Collection {#1185}
                    "field_under_the_edition" => Illuminate\Database\Eloquent\Collection {#1186}
                    "field_under_the_edition_degree" => null
                    "field_cover_description" => "лупа, парень едет на велосипеде"
                    "field_publication_year" => "2008"
                    "field_publication_year_until" => null
                    "field_part" => ""
                    "field_part_writing" => ""
                    "field_second_foreign_language" => null
                    "field_for_whom" => "Учебное издание"
                    "field_allowed" => null
                    "field_reserve_field" => null
                    "field_link_to_source" => null
                    "field_tasks_count" => "459"
                    "field_priority" => null
                    "field_default_folder" => "/fizika_10/gelfgat-z/"
                    "field_isbn" => "978-5-89237-252-7"
                    "field_cover" => array:1 [
                      0 => "/media/fizika_10/gelfgat-z/covers/cover1.webp?ts=1756049816"
                    ]
                    "field_cover_alts" => array:1 [
                      0 => ""
                    ]
                    "field_covers" => array:1 [
                      0 => array:4 [
                        "path" => "/media/fizika_10/gelfgat-z/covers/cover1.webp?ts=1756049816"
                        "alt" => ""
                        "width" => "1566"
                        "height" => "2412"
                      ]
                    ]
                    "field_popular_book" => "0"
                    "field_recommended_books" => Illuminate\Database\Eloquent\Collection {#1187}
                    "field_new_book" => Illuminate\Database\Eloquent\Collection {#1188}
                    "field_old_book" => Illuminate\Database\Eloquent\Collection {#1189}
                    "field_url" => "/10-klass/fizika/gelfgat-zadachnik"
                    "field_cover_color" => Illuminate\Database\Eloquent\Collection {#1190}
                    "field_metatags_title" => null
                    "field_metatags_description" => null
                    "field_h1" => null
                    "field_description_top" => null
                    "field_description_bottom" => null
                    "breadcrumbs" => array:3 [
                      "class" => 381
                      "subject" => 556
                      "class_subject" => 494
                    ]
                  ]
                  #changes: []
                  #casts: []
                  #classCastCache: []
                  #attributeCastCache: []
                  #dateFormat: null
                  #appends: []
                  #dispatchesEvents: []
                  #observables: []
                  #relations: []
                  #touches: []
                  +timestamps: true
                  +usesUniqueIds: false
                  #hidden: []
                  #visible: []
                  #fillable: []
                  #guarded: array:1 [
                    0 => "*"
                  ]
                }
              ]
              #escapeWhenCastingToString: false
            }
            "branch_parent" => Illuminate\Database\Eloquent\Collection {#1192
              #items: []
              #escapeWhenCastingToString: false
            }
          ]
          #original: array:24 [
            "id" => 1319339
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "field_display_title" => "Электродинамика"
            "field_branch_order" => null
            "field_url" => null
            "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1160}
            "field_page_start" => "163"
            "field_branch_display" => "0"
            "field_branch_expanded" => "0"
            "field_display_branch_in_title" => "1"
            "field_display_task_interval" => "0"
            "field_display_branch_page" => "1"
            "field_branch_title_in_content" => "0"
            "field_navigation_title" => null
            "field_metatags_title" => null
            "field_metatags_description" => null
            "field_h1" => null
            "field_description_top" => null
            "field_description_bottom" => null
            "field_branch_cover" => []
            "field_branch_covers" => []
            "book" => Illuminate\Database\Eloquent\Collection {#1194}
            "branch_parent" => Illuminate\Database\Eloquent\Collection {#1192}
          ]
          #changes: []
          #casts: []
          #classCastCache: []
          #attributeCastCache: []
          #dateFormat: null
          #appends: []
          #dispatchesEvents: []
          #observables: []
          #relations: []
          #touches: []
          +timestamps: true
          +usesUniqueIds: false
          #hidden: []
          #visible: []
          #fillable: []
          #guarded: array:1 [
            0 => "*"
          ]
        }
        1 => App\Models\Branch {#1193
          #connection: "mysql"
          #table: "branches"
          #primaryKey: "id"
          #keyType: "int"
          +incrementing: true
          #with: []
          #withCount: []
          +preventsLazyLoading: false
          #perPage: 15
          +exists: true
          +wasRecentlyCreated: false
          #escapeWhenCastingToString: false
          #attributes: array:24 [
            "id" => 1319364
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "field_display_title" => "Магнитное поле"
            "field_branch_order" => null
            "field_url" => null
            "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1195
              #items: []
              #escapeWhenCastingToString: false
            }
            "field_page_start" => "220"
            "field_branch_display" => "0"
            "field_branch_expanded" => "0"
            "field_display_branch_in_title" => "1"
            "field_display_task_interval" => "0"
            "field_display_branch_page" => "1"
            "field_branch_title_in_content" => "0"
            "field_navigation_title" => null
            "field_metatags_title" => null
            "field_metatags_description" => null
            "field_h1" => null
            "field_description_top" => null
            "field_description_bottom" => null
            "field_branch_cover" => []
            "field_branch_covers" => []
            "book" => Illuminate\Database\Eloquent\Collection {#1196
              #items: array:1 [
                0 => App\Models\Book {#1161}
              ]
              #escapeWhenCastingToString: false
            }
            "branch_parent" => Illuminate\Database\Eloquent\Collection {#1197
              #items: array:1 [
                0 => App\Models\Branch {#1034}
              ]
              #escapeWhenCastingToString: false
            }
          ]
          #original: array:24 [
            "id" => 1319364
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "field_display_title" => "Магнитное поле"
            "field_branch_order" => null
            "field_url" => null
            "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1195}
            "field_page_start" => "220"
            "field_branch_display" => "0"
            "field_branch_expanded" => "0"
            "field_display_branch_in_title" => "1"
            "field_display_task_interval" => "0"
            "field_display_branch_page" => "1"
            "field_branch_title_in_content" => "0"
            "field_navigation_title" => null
            "field_metatags_title" => null
            "field_metatags_description" => null
            "field_h1" => null
            "field_description_top" => null
            "field_description_bottom" => null
            "field_branch_cover" => []
            "field_branch_covers" => []
            "book" => Illuminate\Database\Eloquent\Collection {#1196}
            "branch_parent" => Illuminate\Database\Eloquent\Collection {#1197}
          ]
          #changes: []
          #casts: []
          #classCastCache: []
          #attributeCastCache: []
          #dateFormat: null
          #appends: []
          #dispatchesEvents: []
          #observables: []
          #relations: []
          #touches: []
          +timestamps: true
          +usesUniqueIds: false
          #hidden: []
          #visible: []
          #fillable: []
          #guarded: array:1 [
            0 => "*"
          ]
        }
        2 => App\Models\Branch {#1198
          #connection: "mysql"
          #table: "branches"
          #primaryKey: "id"
          #keyType: "int"
          +incrementing: true
          #with: []
          #withCount: []
          +preventsLazyLoading: false
          #perPage: 15
          +exists: true
          +wasRecentlyCreated: false
          #escapeWhenCastingToString: false
          #attributes: array:24 [
            "id" => 1319365
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "field_display_title" => "31. Магнитное поле. Вектор магнитной индукции"
            "field_branch_order" => null
            "field_url" => null
            "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1199
              #items: []
              #escapeWhenCastingToString: false
            }
            "field_page_start" => "220"
            "field_branch_display" => "0"
            "field_branch_expanded" => "0"
            "field_display_branch_in_title" => "1"
            "field_display_task_interval" => "0"
            "field_display_branch_page" => "1"
            "field_branch_title_in_content" => "0"
            "field_navigation_title" => null
            "field_metatags_title" => null
            "field_metatags_description" => null
            "field_h1" => null
            "field_description_top" => null
            "field_description_bottom" => null
            "field_branch_cover" => []
            "field_branch_covers" => []
            "book" => Illuminate\Database\Eloquent\Collection {#1200
              #items: array:1 [
                0 => App\Models\Book {#1161}
              ]
              #escapeWhenCastingToString: false
            }
            "branch_parent" => Illuminate\Database\Eloquent\Collection {#1242
              #items: array:1 [
                0 => App\Models\Branch {#1201
                  #connection: "mysql"
                  #table: "branches"
                  #primaryKey: "id"
                  #keyType: "int"
                  +incrementing: true
                  #with: []
                  #withCount: []
                  +preventsLazyLoading: false
                  #perPage: 15
                  +exists: true
                  +wasRecentlyCreated: false
                  #escapeWhenCastingToString: false
                  #attributes: array:24 [
                    "id" => 1319364
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "field_display_title" => "Магнитное поле"
                    "field_branch_order" => null
                    "field_url" => null
                    "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1203
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_page_start" => "220"
                    "field_branch_display" => "0"
                    "field_branch_expanded" => "0"
                    "field_display_branch_in_title" => "1"
                    "field_display_task_interval" => "0"
                    "field_display_branch_page" => "1"
                    "field_branch_title_in_content" => "0"
                    "field_navigation_title" => null
                    "field_metatags_title" => null
                    "field_metatags_description" => null
                    "field_h1" => null
                    "field_description_top" => null
                    "field_description_bottom" => null
                    "field_branch_cover" => []
                    "field_branch_covers" => []
                    "book" => Illuminate\Database\Eloquent\Collection {#1202
                      #items: array:1 [ …1]
                      #escapeWhenCastingToString: false
                    }
                    "branch_parent" => Illuminate\Database\Eloquent\Collection {#1235
                      #items: array:1 [ …1]
                      #escapeWhenCastingToString: false
                    }
                  ]
                  #original: array:24 [
                    "id" => 1319364
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "field_display_title" => "Магнитное поле"
                    "field_branch_order" => null
                    "field_url" => null
                    "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1203}
                    "field_page_start" => "220"
                    "field_branch_display" => "0"
                    "field_branch_expanded" => "0"
                    "field_display_branch_in_title" => "1"
                    "field_display_task_interval" => "0"
                    "field_display_branch_page" => "1"
                    "field_branch_title_in_content" => "0"
                    "field_navigation_title" => null
                    "field_metatags_title" => null
                    "field_metatags_description" => null
                    "field_h1" => null
                    "field_description_top" => null
                    "field_description_bottom" => null
                    "field_branch_cover" => []
                    "field_branch_covers" => []
                    "book" => Illuminate\Database\Eloquent\Collection {#1202}
                    "branch_parent" => Illuminate\Database\Eloquent\Collection {#1235}
                  ]
                  #changes: []
                  #casts: []
                  #classCastCache: []
                  #attributeCastCache: []
                  #dateFormat: null
                  #appends: []
                  #dispatchesEvents: []
                  #observables: []
                  #relations: []
                  #touches: []
                  +timestamps: true
                  +usesUniqueIds: false
                  #hidden: []
                  #visible: []
                  #fillable: []
                  #guarded: array:1 [
                    0 => "*"
                  ]
                }
              ]
              #escapeWhenCastingToString: false
            }
          ]
          #original: array:24 [
            "id" => 1319365
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "field_display_title" => "31. Магнитное поле. Вектор магнитной индукции"
            "field_branch_order" => null
            "field_url" => null
            "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1199}
            "field_page_start" => "220"
            "field_branch_display" => "0"
            "field_branch_expanded" => "0"
            "field_display_branch_in_title" => "1"
            "field_display_task_interval" => "0"
            "field_display_branch_page" => "1"
            "field_branch_title_in_content" => "0"
            "field_navigation_title" => null
            "field_metatags_title" => null
            "field_metatags_description" => null
            "field_h1" => null
            "field_description_top" => null
            "field_description_bottom" => null
            "field_branch_cover" => []
            "field_branch_covers" => []
            "book" => Illuminate\Database\Eloquent\Collection {#1200}
            "branch_parent" => Illuminate\Database\Eloquent\Collection {#1242}
          ]
          #changes: []
          #casts: []
          #classCastCache: []
          #attributeCastCache: []
          #dateFormat: null
          #appends: []
          #dispatchesEvents: []
          #observables: []
          #relations: []
          #touches: []
          +timestamps: true
          +usesUniqueIds: false
          #hidden: []
          #visible: []
          #fillable: []
          #guarded: array:1 [
            0 => "*"
          ]
        }
        3 => App\Models\Branch {#1240
          #connection: "mysql"
          #table: "branches"
          #primaryKey: "id"
          #keyType: "int"
          +incrementing: true
          #with: []
          #withCount: []
          +preventsLazyLoading: false
          #perPage: 15
          +exists: true
          +wasRecentlyCreated: false
          #escapeWhenCastingToString: false
          #attributes: array:24 [
            "id" => 1319366
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "field_display_title" => "Упражнения"
            "field_branch_order" => null
            "field_url" => null
            "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1241
              #items: []
              #escapeWhenCastingToString: false
            }
            "field_page_start" => "220"
            "field_branch_display" => "0"
            "field_branch_expanded" => "0"
            "field_display_branch_in_title" => "1"
            "field_display_task_interval" => "0"
            "field_display_branch_page" => "1"
            "field_branch_title_in_content" => "0"
            "field_navigation_title" => null
            "field_metatags_title" => null
            "field_metatags_description" => null
            "field_h1" => null
            "field_description_top" => null
            "field_description_bottom" => null
            "field_branch_cover" => []
            "field_branch_covers" => []
            "book" => Illuminate\Database\Eloquent\Collection {#1243
              #items: array:1 [
                0 => App\Models\Book {#1161}
              ]
              #escapeWhenCastingToString: false
            }
            "branch_parent" => Illuminate\Database\Eloquent\Collection {#1252
              #items: array:1 [
                0 => App\Models\Branch {#1251
                  #connection: "mysql"
                  #table: "branches"
                  #primaryKey: "id"
                  #keyType: "int"
                  +incrementing: true
                  #with: []
                  #withCount: []
                  +preventsLazyLoading: false
                  #perPage: 15
                  +exists: true
                  +wasRecentlyCreated: false
                  #escapeWhenCastingToString: false
                  #attributes: array:24 [
                    "id" => 1319365
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "field_display_title" => "31. Магнитное поле. Вектор магнитной индукции"
                    "field_branch_order" => null
                    "field_url" => null
                    "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1253
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_page_start" => "220"
                    "field_branch_display" => "0"
                    "field_branch_expanded" => "0"
                    "field_display_branch_in_title" => "1"
                    "field_display_task_interval" => "0"
                    "field_display_branch_page" => "1"
                    "field_branch_title_in_content" => "0"
                    "field_navigation_title" => null
                    "field_metatags_title" => null
                    "field_metatags_description" => null
                    "field_h1" => null
                    "field_description_top" => null
                    "field_description_bottom" => null
                    "field_branch_cover" => []
                    "field_branch_covers" => []
                    "book" => Illuminate\Database\Eloquent\Collection {#1254
                      #items: array:1 [ …1]
                      #escapeWhenCastingToString: false
                    }
                    "branch_parent" => Illuminate\Database\Eloquent\Collection {#1255
                      #items: array:1 [ …1]
                      #escapeWhenCastingToString: false
                    }
                  ]
                  #original: array:24 [
                    "id" => 1319365
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "field_display_title" => "31. Магнитное поле. Вектор магнитной индукции"
                    "field_branch_order" => null
                    "field_url" => null
                    "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1253}
                    "field_page_start" => "220"
                    "field_branch_display" => "0"
                    "field_branch_expanded" => "0"
                    "field_display_branch_in_title" => "1"
                    "field_display_task_interval" => "0"
                    "field_display_branch_page" => "1"
                    "field_branch_title_in_content" => "0"
                    "field_navigation_title" => null
                    "field_metatags_title" => null
                    "field_metatags_description" => null
                    "field_h1" => null
                    "field_description_top" => null
                    "field_description_bottom" => null
                    "field_branch_cover" => []
                    "field_branch_covers" => []
                    "book" => Illuminate\Database\Eloquent\Collection {#1254}
                    "branch_parent" => Illuminate\Database\Eloquent\Collection {#1255}
                  ]
                  #changes: []
                  #casts: []
                  #classCastCache: []
                  #attributeCastCache: []
                  #dateFormat: null
                  #appends: []
                  #dispatchesEvents: []
                  #observables: []
                  #relations: []
                  #touches: []
                  +timestamps: true
                  +usesUniqueIds: false
                  #hidden: []
                  #visible: []
                  #fillable: []
                  #guarded: array:1 [
                    0 => "*"
                  ]
                }
              ]
              #escapeWhenCastingToString: false
            }
          ]
          #original: array:24 [
            "id" => 1319366
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "field_display_title" => "Упражнения"
            "field_branch_order" => null
            "field_url" => null
            "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1241}
            "field_page_start" => "220"
            "field_branch_display" => "0"
            "field_branch_expanded" => "0"
            "field_display_branch_in_title" => "1"
            "field_display_task_interval" => "0"
            "field_display_branch_page" => "1"
            "field_branch_title_in_content" => "0"
            "field_navigation_title" => null
            "field_metatags_title" => null
            "field_metatags_description" => null
            "field_h1" => null
            "field_description_top" => null
            "field_description_bottom" => null
            "field_branch_cover" => []
            "field_branch_covers" => []
            "book" => Illuminate\Database\Eloquent\Collection {#1243}
            "branch_parent" => Illuminate\Database\Eloquent\Collection {#1252}
          ]
          #changes: []
          #casts: []
          #classCastCache: []
          #attributeCastCache: []
          #dateFormat: null
          #appends: []
          #dispatchesEvents: []
          #observables: []
          #relations: []
          #touches: []
          +timestamps: true
          +usesUniqueIds: false
          #hidden: []
          #visible: []
          #fillable: []
          #guarded: array:1 [
            0 => "*"
          ]
        }
      ]
      #escapeWhenCastingToString: false
    }
    "content" => Illuminate\Database\Eloquent\Collection {#1108
      #items: array:2 [
        0 => App\Models\Element {#1138
          #connection: "mysql"
          #table: "elements"
          #primaryKey: "id"
          #keyType: "int"
          +incrementing: true
          #with: []
          #withCount: []
          +preventsLazyLoading: false
          #perPage: 15
          +exists: true
          +wasRecentlyCreated: false
          #escapeWhenCastingToString: false
          #attributes: array:7 [
            "id" => 1493910
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "edition" => Illuminate\Database\Eloquent\Collection {#1128
              #items: array:1 [
                0 => App\Models\Edition {#1137
                  #connection: "mysql"
                  #table: "editions"
                  #primaryKey: "id"
                  #keyType: "int"
                  +incrementing: false
                  #with: []
                  #withCount: []
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                    "created_at" => "2026-04-10 13:58:26"
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                    "title" => "Условие"
                    "field_order" => "1"
                    "field_publisher" => Illuminate\Database\Eloquent\Collection {#1135
                      #items: array:1 [ …1]
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                    "field_responsible" => Illuminate\Database\Eloquent\Collection {#1134
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                    "field_publisher" => Illuminate\Database\Eloquent\Collection {#1135}
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                    "field_moderator" => "stas"
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                    "field_responsible" => Illuminate\Database\Eloquent\Collection {#1134}
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                    "field_similar_book" => Illuminate\Database\Eloquent\Collection {#1132}
                    "field_process_formula" => "katex"
                    "field_edition_group" => Illuminate\Database\Eloquent\Collection {#1133}
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              #escapeWhenCastingToString: false
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            "task" => array:2 [
              "refs" => "1319749"
              "type" => "task"
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            "text" => "<p><strong>31.3.</strong> Электрон влетает со скоростью $\vec{v}$ в однородное магнитное поле с индукцией $\vec{B}$. Скорость электрона направлена перпендикулярно вектору $\vec{B}$. По какой траектории будет двигаться электрон?</p><p>☑ По окружности радиусом $R = mv/(eB)$.</p><p><strong>Решение.</strong> На электрон действует сила Лоренца $F_{\text{Л}} = eBv$, перпендикулярная вектору $\vec{B}$. Поскольку начальная скорость электрона также перпендикулярна $\vec{B}$, его траектория лежит в одной плоскости (перпендикулярной вектору $\vec{B}$). Работа силы Лоренца равна нулю, поэтому $v = \text{const}$; электрон движется с постоянным по модулю ускорением ($a = F_{\text{Л}}/m = eBv/m$), которое перпендикулярно скорости. Перечисленным условиям удовлетворяет только одна траектория — окружность, радиус которой можно найти из соотношения $a = v^2/R$.</p>"
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                "height" => 1019
                "path" => "/media/fizika_10/gelfgat-z/0-31/3-1.webp?ts=1756251127"
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            ]
          ]
          #original: array:7 [
            "id" => 1493910
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "edition" => Illuminate\Database\Eloquent\Collection {#1128}
            "task" => array:2 [
              "refs" => "1319749"
              "type" => "task"
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            "text" => "<p><strong>31.3.</strong> Электрон влетает со скоростью $\vec{v}$ в однородное магнитное поле с индукцией $\vec{B}$. Скорость электрона направлена перпендикулярно вектору $\vec{B}$. По какой траектории будет двигаться электрон?</p><p>☑ По окружности радиусом $R = mv/(eB)$.</p><p><strong>Решение.</strong> На электрон действует сила Лоренца $F_{\text{Л}} = eBv$, перпендикулярная вектору $\vec{B}$. Поскольку начальная скорость электрона также перпендикулярна $\vec{B}$, его траектория лежит в одной плоскости (перпендикулярной вектору $\vec{B}$). Работа силы Лоренца равна нулю, поэтому $v = \text{const}$; электрон движется с постоянным по модулю ускорением ($a = F_{\text{Л}}/m = eBv/m$), которое перпендикулярно скорости. Перечисленным условиям удовлетворяет только одна траектория — окружность, радиус которой можно найти из соотношения $a = v^2/R$.</p>"
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          #connection: "mysql"
          #table: "elements"
          #primaryKey: "id"
          #keyType: "int"
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          #attributes: array:6 [
            "id" => 1691467
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "edition" => Illuminate\Database\Eloquent\Collection {#1122
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                0 => App\Models\Edition {#1130
                  #connection: "mysql"
                  #table: "editions"
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                  +incrementing: false
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                    "created_at" => "2026-04-10 13:58:26"
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                    "title" => "Решение"
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                    "field_publisher" => Illuminate\Database\Eloquent\Collection {#1126
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                    "field_moderator" => "tolik"
                    "field_edition_type" => "solution"
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                    "id" => 6138
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "title" => "Решение"
                    "field_order" => "2"
                    "field_publisher" => Illuminate\Database\Eloquent\Collection {#1126}
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            "text" => "<p><strong>Дано:</strong></p><p>Заряд электрона: $q = -e$ (где $e = 1.6 \cdot 10^{-19}$ Кл - элементарный заряд)</p><p>Масса электрона: $m$</p><p>Скорость электрона: $\vec{v}$</p><p>Индукция магнитного поля: $\vec{B}$</p><p>Условие: $\vec{v} \perp \vec{B}$</p><p><strong>Найти:</strong></p><p>Траекторию движения электрона.</p><p><strong>Решение:</strong></p><p>На заряженную частицу, движущуюся в магнитном поле, действует сила Лоренца, которая определяется векторным произведением:</p><p>$\vec{F_Л} = q(\vec{v} \times \vec{B})$</p><p>Для электрона заряд $q = -e$, поэтому:</p><p>$\vec{F_Л} = -e(\vec{v} \times \vec{B})$</p><p>По определению векторного произведения, вектор силы Лоренца $\vec{F_Л}$ перпендикулярен и вектору скорости $\vec{v}$, и вектору магнитной индукции $\vec{B}$.</p><p>Модуль силы Лоренца равен:</p><p>$F_Л = |q|vB\sin\alpha = evB\sin\alpha$</p><p>где $\alpha$ — угол между векторами $\vec{v}$ и $\vec{B}$. По условию задачи скорость электрона перпендикулярна вектору магнитной индукции, следовательно, $\alpha = 90^\circ$, и $\sin(90^\circ) = 1$. Тогда модуль силы Лоренца принимает максимальное значение:</p><p>$F_Л = evB$</p><p>Так как сила Лоренца всегда перпендикулярна вектору скорости, она не совершает работы над электроном ($A = \vec{F} \cdot \Delta\vec{r} = 0$, так как $\vec{F} \perp \vec{v}$ и, соответственно, $\vec{F} \perp \Delta\vec{r}$). Согласно теореме о кинетической энергии, если работа не совершается, то кинетическая энергия частицы не изменяется. Это означает, что модуль скорости электрона $v$ остается постоянным ($v = \text{const}$).</p><p>Сила, которая постоянно действует перпендикулярно скорости и имеет постоянный модуль, является центростремительной силой. Она заставляет тело двигаться по окружности с постоянной по модулю скоростью. Таким образом, электрон будет двигаться по окружности в плоскости, перпендикулярной вектору $\vec{B}$.</p><p>Согласно второму закону Ньютона, сила Лоренца сообщает электрону центростремительное ускорение $a_ц = \frac{v^2}{R}$:</p><p>$F_Л = ma_ц$</p><p>$evB = m\frac{v^2}{R}$</p><p>Из этого соотношения можно выразить радиус траектории $R$:</p><p>$eB = \frac{mv}{R}$</p><p>$R = \frac{mv}{eB}$</p><p>Таким образом, электрон будет двигаться по окружности, радиус которой зависит от его массы, скорости, заряда и индукции магнитного поля.</p><p><strong>Ответ:</strong> Электрон будет двигаться по окружности радиусом $R = \frac{mv}{eB}$.</p>"
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            "id" => 1691467
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "edition" => Illuminate\Database\Eloquent\Collection {#1122}
            "task" => array:2 [
              "refs" => "1319749"
              "type" => "task"
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            "text" => "<p><strong>Дано:</strong></p><p>Заряд электрона: $q = -e$ (где $e = 1.6 \cdot 10^{-19}$ Кл - элементарный заряд)</p><p>Масса электрона: $m$</p><p>Скорость электрона: $\vec{v}$</p><p>Индукция магнитного поля: $\vec{B}$</p><p>Условие: $\vec{v} \perp \vec{B}$</p><p><strong>Найти:</strong></p><p>Траекторию движения электрона.</p><p><strong>Решение:</strong></p><p>На заряженную частицу, движущуюся в магнитном поле, действует сила Лоренца, которая определяется векторным произведением:</p><p>$\vec{F_Л} = q(\vec{v} \times \vec{B})$</p><p>Для электрона заряд $q = -e$, поэтому:</p><p>$\vec{F_Л} = -e(\vec{v} \times \vec{B})$</p><p>По определению векторного произведения, вектор силы Лоренца $\vec{F_Л}$ перпендикулярен и вектору скорости $\vec{v}$, и вектору магнитной индукции $\vec{B}$.</p><p>Модуль силы Лоренца равен:</p><p>$F_Л = |q|vB\sin\alpha = evB\sin\alpha$</p><p>где $\alpha$ — угол между векторами $\vec{v}$ и $\vec{B}$. По условию задачи скорость электрона перпендикулярна вектору магнитной индукции, следовательно, $\alpha = 90^\circ$, и $\sin(90^\circ) = 1$. Тогда модуль силы Лоренца принимает максимальное значение:</p><p>$F_Л = evB$</p><p>Так как сила Лоренца всегда перпендикулярна вектору скорости, она не совершает работы над электроном ($A = \vec{F} \cdot \Delta\vec{r} = 0$, так как $\vec{F} \perp \vec{v}$ и, соответственно, $\vec{F} \perp \Delta\vec{r}$). Согласно теореме о кинетической энергии, если работа не совершается, то кинетическая энергия частицы не изменяется. Это означает, что модуль скорости электрона $v$ остается постоянным ($v = \text{const}$).</p><p>Сила, которая постоянно действует перпендикулярно скорости и имеет постоянный модуль, является центростремительной силой. Она заставляет тело двигаться по окружности с постоянной по модулю скоростью. Таким образом, электрон будет двигаться по окружности в плоскости, перпендикулярной вектору $\vec{B}$.</p><p>Согласно второму закону Ньютона, сила Лоренца сообщает электрону центростремительное ускорение $a_ц = \frac{v^2}{R}$:</p><p>$F_Л = ma_ц$</p><p>$evB = m\frac{v^2}{R}$</p><p>Из этого соотношения можно выразить радиус траектории $R$:</p><p>$eB = \frac{mv}{R}$</p><p>$R = \frac{mv}{eB}$</p><p>Таким образом, электрон будет двигаться по окружности, радиус которой зависит от его массы, скорости, заряда и индукции магнитного поля.</p><p><strong>Ответ:</strong> Электрон будет двигаться по окружности радиусом $R = \frac{mv}{eB}$.</p>"
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            "created_at" => "2026-04-10 13:58:26"
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            "field_page_start" => "221"
            "field_url" => "/10-klass/fizika/gelfgat-zadachnik/page-221"
            "field_display_title" => "221"
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              #items: []
              #escapeWhenCastingToString: false
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            "content" => Illuminate\Database\Eloquent\Collection {#1110
              #items: array:1 [
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                  #connection: "mysql"
                  #table: "elements"
                  #primaryKey: "id"
                  #keyType: "int"
                  +incrementing: true
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                  +exists: true
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                  #attributes: array:6 [
                    "id" => 1519727
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "edition" => Illuminate\Database\Eloquent\Collection {#1109
                      #items: array:1 [ …1]
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                    "book_page" => array:2 [
                      "refs" => "1341182"
                      "type" => "book_page"
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                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "edition" => Illuminate\Database\Eloquent\Collection {#1109}
                    "book_page" => array:2 [
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                      "type" => "book_page"
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            "tasks" => Illuminate\Database\Eloquent\Collection {#1349
              #items: array:3 [
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                  #connection: "mysql"
                  #table: "tasks"
                  #primaryKey: "id"
                  #keyType: "int"
                  +incrementing: true
                  #with: []
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                  +preventsLazyLoading: false
                  #perPage: 15
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№31.3 (с. 221)
Условие. №31.3 (с. 221)
скриншот условия
Физика, 10-11 класс Задачник, авторы: Гельфгат Илья Маркович, Генденштейн Лев Элевич, Кирик Леонид Анатольевич, издательство Илекса, Москва, 2008, красного цвета, страница 221, номер 31.3, Условие

31.3. Электрон влетает со скоростью $\vec{v}$ в однородное магнитное поле с индукцией $\vec{B}$. Скорость электрона направлена перпендикулярно вектору $\vec{B}$. По какой траектории будет двигаться электрон?

☑ По окружности радиусом $R = mv/(eB)$.

Решение. На электрон действует сила Лоренца $F_{\text{Л}} = eBv$, перпендикулярная вектору $\vec{B}$. Поскольку начальная скорость электрона также перпендикулярна $\vec{B}$, его траектория лежит в одной плоскости (перпендикулярной вектору $\vec{B}$). Работа силы Лоренца равна нулю, поэтому $v = \text{const}$; электрон движется с постоянным по модулю ускорением ($a = F_{\text{Л}}/m = eBv/m$), которое перпендикулярно скорости. Перечисленным условиям удовлетворяет только одна траектория — окружность, радиус которой можно найти из соотношения $a = v^2/R$.

Решение. №31.3 (с. 221)

Дано:

Заряд электрона: $q = -e$ (где $e = 1.6 \cdot 10^{-19}$ Кл - элементарный заряд)

Масса электрона: $m$

Скорость электрона: $\vec{v}$

Индукция магнитного поля: $\vec{B}$

Условие: $\vec{v} \perp \vec{B}$

Найти:

Траекторию движения электрона.

Решение:

На заряженную частицу, движущуюся в магнитном поле, действует сила Лоренца, которая определяется векторным произведением:

$\vec{F_Л} = q(\vec{v} \times \vec{B})$

Для электрона заряд $q = -e$, поэтому:

$\vec{F_Л} = -e(\vec{v} \times \vec{B})$

По определению векторного произведения, вектор силы Лоренца $\vec{F_Л}$ перпендикулярен и вектору скорости $\vec{v}$, и вектору магнитной индукции $\vec{B}$.

Модуль силы Лоренца равен:

$F_Л = |q|vB\sin\alpha = evB\sin\alpha$

где $\alpha$ — угол между векторами $\vec{v}$ и $\vec{B}$. По условию задачи скорость электрона перпендикулярна вектору магнитной индукции, следовательно, $\alpha = 90^\circ$, и $\sin(90^\circ) = 1$. Тогда модуль силы Лоренца принимает максимальное значение:

$F_Л = evB$

Так как сила Лоренца всегда перпендикулярна вектору скорости, она не совершает работы над электроном ($A = \vec{F} \cdot \Delta\vec{r} = 0$, так как $\vec{F} \perp \vec{v}$ и, соответственно, $\vec{F} \perp \Delta\vec{r}$). Согласно теореме о кинетической энергии, если работа не совершается, то кинетическая энергия частицы не изменяется. Это означает, что модуль скорости электрона $v$ остается постоянным ($v = \text{const}$).

Сила, которая постоянно действует перпендикулярно скорости и имеет постоянный модуль, является центростремительной силой. Она заставляет тело двигаться по окружности с постоянной по модулю скоростью. Таким образом, электрон будет двигаться по окружности в плоскости, перпендикулярной вектору $\vec{B}$.

Согласно второму закону Ньютона, сила Лоренца сообщает электрону центростремительное ускорение $a_ц = \frac{v^2}{R}$:

$F_Л = ma_ц$

$evB = m\frac{v^2}{R}$

Из этого соотношения можно выразить радиус траектории $R$:

$eB = \frac{mv}{R}$

$R = \frac{mv}{eB}$

Таким образом, электрон будет двигаться по окружности, радиус которой зависит от его массы, скорости, заряда и индукции магнитного поля.

Ответ: Электрон будет двигаться по окружности радиусом $R = \frac{mv}{eB}$.

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