Номер 138, страница 244 - 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. Электромагнитные колебания и волны. 33. Свободные электромагнитные колебания. Переменный ток. Олимпиадные задачи - номер 138, страница 244.

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                              "field_accusative_case" => "десятый"
                              "field_creative_case" => "десятым"
                              "field_dative_case" => "десятому"
                              "field_genitive_case" => "десятого"
                              "field_nominative_case" => "десятый"
                              "field_prepositional_case" => "десятом"
                            ]
                            "field_translit" => "desjatyj"
                          ]
                          #original: array:6 [
                            "id" => 5459
                            "created_at" => "2026-04-10 13:58:26"
                            "updated_at" => null
                            "name" => "10"
                            "field_cases" => array:6 [
                              "field_accusative_case" => "десятый"
                              "field_creative_case" => "десятым"
                              "field_dative_case" => "десятому"
                              "field_genitive_case" => "десятого"
                              "field_nominative_case" => "десятый"
                              "field_prepositional_case" => "десятом"
                            ]
                            "field_translit" => "desjatyj"
                          ]
                          #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 {#1185
                          #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" => 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"
                          ]
                          #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 {#1175
                      #items: array:1 [
                        0 => App\Models\Term {#1181
                          #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 {#1183
                      #items: array:3 [
                        0 => App\Models\Term {#1190
                          #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 {#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: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 {#1192
                          #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 {#1187
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_book_type" => Illuminate\Database\Eloquent\Collection {#1188
                      #items: array:1 [
                        0 => App\Models\Term {#1173
                          #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 {#1179
                      #items: array:1 [
                        0 => App\Models\Term {#1186
                          #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 {#1177
                      #items: array:1 [
                        0 => App\Models\Term {#1180
                          #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 {#1178
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_umk" => Illuminate\Database\Eloquent\Collection {#1172
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_level_of_education" => Illuminate\Database\Eloquent\Collection {#1202
                      #items: array:1 [
                        0 => App\Models\Term {#1201
                          #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 {#1194
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_publication_number" => null
                    "field_publication_type" => Illuminate\Database\Eloquent\Collection {#1195
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_under_the_edition" => Illuminate\Database\Eloquent\Collection {#1193
                      #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 {#1198
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_new_book" => Illuminate\Database\Eloquent\Collection {#1196
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_old_book" => Illuminate\Database\Eloquent\Collection {#1199
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_url" => "/10-klass/fizika/gelfgat-zadachnik"
                    "field_cover_color" => Illuminate\Database\Eloquent\Collection {#1205
                      #items: array:1 [
                        0 => App\Models\Term {#1197
                          #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 {#1174}
                    "field_class" => Illuminate\Database\Eloquent\Collection {#1176}
                    "field_publisher" => Illuminate\Database\Eloquent\Collection {#1175}
                    "field_author" => Illuminate\Database\Eloquent\Collection {#1183}
                    "field_author_foreign" => Illuminate\Database\Eloquent\Collection {#1187}
                    "field_book_type" => Illuminate\Database\Eloquent\Collection {#1188}
                    "field_country" => Illuminate\Database\Eloquent\Collection {#1179}
                    "field_city" => Illuminate\Database\Eloquent\Collection {#1177}
                    "field_series" => Illuminate\Database\Eloquent\Collection {#1178}
                    "field_umk" => Illuminate\Database\Eloquent\Collection {#1172}
                    "field_level_of_education" => Illuminate\Database\Eloquent\Collection {#1202}
                    "field_standart_of_education" => Illuminate\Database\Eloquent\Collection {#1194}
                    "field_publication_number" => null
                    "field_publication_type" => Illuminate\Database\Eloquent\Collection {#1195}
                    "field_under_the_edition" => Illuminate\Database\Eloquent\Collection {#1193}
                    "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 {#1198}
                    "field_new_book" => Illuminate\Database\Eloquent\Collection {#1196}
                    "field_old_book" => Illuminate\Database\Eloquent\Collection {#1199}
                    "field_url" => "/10-klass/fizika/gelfgat-zadachnik"
                    "field_cover_color" => Illuminate\Database\Eloquent\Collection {#1205}
                    "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 {#1162
              #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 {#1170}
            "branch_parent" => Illuminate\Database\Eloquent\Collection {#1162}
          ]
          #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 {#1163
          #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" => 1319371
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "field_display_title" => "Электромагнитные колебания и волны"
            "field_branch_order" => null
            "field_url" => null
            "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1161
              #items: []
              #escapeWhenCastingToString: false
            }
            "field_page_start" => "241"
            "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 {#1166
              #items: array:1 [
                0 => App\Models\Book {#1169}
              ]
              #escapeWhenCastingToString: false
            }
            "branch_parent" => Illuminate\Database\Eloquent\Collection {#1164
              #items: array:1 [
                0 => App\Models\Branch {#1034}
              ]
              #escapeWhenCastingToString: false
            }
          ]
          #original: array:24 [
            "id" => 1319371
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "field_display_title" => "Электромагнитные колебания и волны"
            "field_branch_order" => null
            "field_url" => null
            "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1161}
            "field_page_start" => "241"
            "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 {#1166}
            "branch_parent" => Illuminate\Database\Eloquent\Collection {#1164}
          ]
          #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 {#1167
          #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" => 1319372
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "field_display_title" => "33. Свободные электромагнитные колебания. Переменный ток"
            "field_branch_order" => null
            "field_url" => null
            "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1165
              #items: []
              #escapeWhenCastingToString: false
            }
            "field_page_start" => "241"
            "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 {#1204
              #items: array:1 [
                0 => App\Models\Book {#1169}
              ]
              #escapeWhenCastingToString: false
            }
            "branch_parent" => Illuminate\Database\Eloquent\Collection {#1246
              #items: array:1 [
                0 => App\Models\Branch {#1203
                  #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" => 1319371
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "field_display_title" => "Электромагнитные колебания и волны"
                    "field_branch_order" => null
                    "field_url" => null
                    "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1207
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_page_start" => "241"
                    "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 {#1206
                      #items: array:1 [
                        0 => App\Models\Book {#1208 …30}
                      ]
                      #escapeWhenCastingToString: false
                    }
                    "branch_parent" => Illuminate\Database\Eloquent\Collection {#1239
                      #items: array:1 [
                        0 => App\Models\Branch {#1240 …30}
                      ]
                      #escapeWhenCastingToString: false
                    }
                  ]
                  #original: array:24 [
                    "id" => 1319371
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "field_display_title" => "Электромагнитные колебания и волны"
                    "field_branch_order" => null
                    "field_url" => null
                    "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1207}
                    "field_page_start" => "241"
                    "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 {#1206}
                    "branch_parent" => Illuminate\Database\Eloquent\Collection {#1239}
                  ]
                  #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" => 1319372
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "field_display_title" => "33. Свободные электромагнитные колебания. Переменный ток"
            "field_branch_order" => null
            "field_url" => null
            "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1165}
            "field_page_start" => "241"
            "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 {#1204}
            "branch_parent" => Illuminate\Database\Eloquent\Collection {#1246}
          ]
          #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 {#1244
          #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" => 1319374
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "field_display_title" => "Олимпиадные задачи"
            "field_branch_order" => null
            "field_url" => null
            "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1245
              #items: []
              #escapeWhenCastingToString: false
            }
            "field_page_start" => "243"
            "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 {#1247
              #items: array:1 [
                0 => App\Models\Book {#1169}
              ]
              #escapeWhenCastingToString: false
            }
            "branch_parent" => Illuminate\Database\Eloquent\Collection {#1256
              #items: array:1 [
                0 => App\Models\Branch {#1255
                  #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" => 1319372
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "field_display_title" => "33. Свободные электромагнитные колебания. Переменный ток"
                    "field_branch_order" => null
                    "field_url" => null
                    "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1257
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_page_start" => "241"
                    "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 {#1258
                      #items: array:1 [
                        0 => App\Models\Book {#1169}
                      ]
                      #escapeWhenCastingToString: false
                    }
                    "branch_parent" => Illuminate\Database\Eloquent\Collection {#1259
                      #items: array:1 [
                        0 => App\Models\Branch {#1203}
                      ]
                      #escapeWhenCastingToString: false
                    }
                  ]
                  #original: array:24 [
                    "id" => 1319372
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "field_display_title" => "33. Свободные электромагнитные колебания. Переменный ток"
                    "field_branch_order" => null
                    "field_url" => null
                    "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1257}
                    "field_page_start" => "241"
                    "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 {#1258}
                    "branch_parent" => Illuminate\Database\Eloquent\Collection {#1259}
                  ]
                  #changes: []
                  #casts: []
                  #classCastCache: []
                  #attributeCastCache: []
                  #dateFormat: null
                  #appends: []
                  #dispatchesEvents: []
                  #observables: []
                  #relations: []
                  #touches: []
                  +timestamps: true
                  +usesUniqueIds: false
                  #hidden: []
                  #visible: []
                  #fillable: []
                  #guarded: array:1 [
                    0 => "*"
                  ]
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            "text" => "<p><strong>O38.</strong> Неоновая лампа с напряжением зажигания $U_3 = 156$ В включена в сеть 220 В, 50 Гц. Найдите частоту $\text{n}$ вспышек лампы. В течение какой части периода лампа горит? Напряжение гашения лампы считайте равным напряжению зажигания.</p><p>&#9745; $n = 100 \text{ с}^{}$; лампа горит 2/3 периода.</p><p><strong><em>Решение.</em></strong> Выберем начало отсчета времени так, чтобы напряжение в сети изменялось по закону $u = U_M \sin\omega t$, где $U_M = \sqrt{2} \cdot 220 \text{ (В)} = 311 \text{ (В)}$. Неоновая лампа горит, когда $|u| \geq U_3$ (на рисунке соответствующие промежутки времени выделены). За период происходят две вспышки, поэтому $n = 100 \text{ с}^{}$. Продолжительность каждой вспышки равна $\Delta t = t_2 - t_1 = \frac{T}{2} - \frac{T}{\pi} \arcsin \frac{U_3}{U_M}$, т. е. лампа горит в течение доли периода $\frac{2\Delta t}{T} = 1 - \frac{2}{\pi} \arcsin \frac{U_3}{U_M} = 0,67$.</p>"
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            "text" => "<p><strong>O38.</strong> Неоновая лампа с напряжением зажигания $U_3 = 156$ В включена в сеть 220 В, 50 Гц. Найдите частоту $\text{n}$ вспышек лампы. В течение какой части периода лампа горит? Напряжение гашения лампы считайте равным напряжению зажигания.</p><p>&#9745; $n = 100 \text{ с}^{}$; лампа горит 2/3 периода.</p><p><strong><em>Решение.</em></strong> Выберем начало отсчета времени так, чтобы напряжение в сети изменялось по закону $u = U_M \sin\omega t$, где $U_M = \sqrt{2} \cdot 220 \text{ (В)} = 311 \text{ (В)}$. Неоновая лампа горит, когда $|u| \geq U_3$ (на рисунке соответствующие промежутки времени выделены). За период происходят две вспышки, поэтому $n = 100 \text{ с}^{}$. Продолжительность каждой вспышки равна $\Delta t = t_2 - t_1 = \frac{T}{2} - \frac{T}{\pi} \arcsin \frac{U_3}{U_M}$, т. е. лампа горит в течение доли периода $\frac{2\Delta t}{T} = 1 - \frac{2}{\pi} \arcsin \frac{U_3}{U_M} = 0,67$.</p>"
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            "text" => "<p><strong>Дано:</strong></p><p>Напряжение зажигания (и гашения) неоновой лампы, $U_з = 156 \text{ В}$</p><p>Действующее (эффективное) напряжение в сети, $U_{действ} = 220 \text{ В}$</p><p>Частота переменного тока в сети, $\nu = 50 \text{ Гц}$</p><p>Все величины представлены в системе СИ.</p><p><strong>Найти:</strong></p><p><strong>1.</strong> Частоту вспышек лампы, $n$</p><p><strong>2.</strong> Часть периода, в течение которой лампа горит, $\frac{\Delta t_{общ}}{T}$</p><p><strong>Решение:</strong></p><p><strong>Частота n вспышек лампы</strong></p><p>Напряжение в сети изменяется по синусоидальному закону. Неоновая лампа загорается, когда мгновенное значение напряжения по модулю становится равным или превышает напряжение зажигания $|u(t)| \ge U_з$.</p><p>За один период $T$ переменного тока напряжение дважды достигает значений, достаточных для зажигания лампы: один раз в положительной полуволне и один раз в отрицательной. Следовательно, за один период колебаний напряжения в сети лампа вспыхивает дважды. Это означает, что частота вспышек лампы $n$ в два раза больше частоты переменного тока $\nu$.</p><p>$n = 2\nu = 2 \cdot 50 \text{ Гц} = 100 \text{ Гц} = 100 \text{ с}^{-1}$</p><p><strong>Ответ:</strong> $n = 100 \text{ с}^{-1}$.</p><p><strong>В течение какой части периода лампа горит?</strong></p><p>Мгновенное значение напряжения в сети описывается уравнением $u(t) = U_м \sin(\omega t)$, где $U_м$ — амплитудное значение напряжения, а $\omega$ — циклическая частота.</p><p>Амплитудное напряжение связано с действующим напряжением соотношением:</p><p>$U_м = U_{действ} \cdot \sqrt{2} = 220 \cdot \sqrt{2} \approx 311 \text{ В}$</p><p>Лампа горит, когда $|u(t)| \ge U_з$, то есть $|U_м \sin(\omega t)| \ge U_з$.</p><p>Рассмотрим первую положительную полуволну ($0 \le t \le T/2$). Лампа зажжется в момент времени $t_1$, когда $u(t_1) = U_з$, и погаснет в момент $t_2$, когда напряжение снова станет равным $U_з$.</p><p>$U_з = U_м \sin(\omega t_1)$</p><p>Отсюда фаза зажигания: $\omega t_1 = \arcsin\left(\frac{U_з}{U_м}\right)$.</p><p>Из симметрии синусоиды относительно момента времени $t = T/4$ (когда напряжение максимально), момент погасания $t_2$ можно найти как $t_2 = T/2 - t_1$.</p><p>Длительность одной вспышки в положительной полуволне: $\Delta t_1 = t_2 - t_1 = (T/2 - t_1) - t_1 = T/2 - 2t_1$.</p><p>Так как $\omega = \frac{2\pi}{T}$, то $t_1 = \frac{1}{\omega}\arcsin\left(\frac{U_з}{U_м}\right) = \frac{T}{2\pi}\arcsin\left(\frac{U_з}{U_м}\right)$.</p><p>Подставим $t_1$ в выражение для $\Delta t_1$:</p><p>$\Delta t_1 = \frac{T}{2} - 2 \cdot \frac{T}{2\pi}\arcsin\left(\frac{U_з}{U_м}\right) = \frac{T}{2} - \frac{T}{\pi}\arcsin\left(\frac{U_з}{U_м}\right)$</p><p>Поскольку за один период происходит две одинаковые по длительности вспышки (в положительной и отрицательной полуволнах), общая длительность горения лампы за период $T$ равна $\Delta t_{общ} = 2\Delta t_1$.</p><p>$\Delta t_{общ} = 2 \left( \frac{T}{2} - \frac{T}{\pi}\arcsin\left(\frac{U_з}{U_м}\right) \right) = T - \frac{2T}{\pi}\arcsin\left(\frac{U_з}{U_м}\right)$</p><p>Чтобы найти, какую часть периода лампа горит, разделим $\Delta t_{общ}$ на $T$:</p><p>$\frac{\Delta t_{общ}}{T} = 1 - \frac{2}{\pi}\arcsin\left(\frac{U_з}{U_м}\right)$</p><p>Подставим числовые значения (аргумент арксинуса вычисляется в радианах):</p><p>$\frac{\Delta t_{общ}}{T} = 1 - \frac{2}{\pi}\arcsin\left(\frac{156}{311}\right) \approx 1 - \frac{2}{3.1416}\arcsin(0.5016) \approx 1 - 0.6366 \cdot 0.5253 \approx 1 - 0.3344 \approx 0.6656$</p><p>Это значение близко к $2/3 \approx 0.667$.</p><p><strong>Ответ:</strong> лампа горит в течение $0.67$ периода (или примерно $2/3$ периода).</p>"
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            "text" => "<p><strong>Дано:</strong></p><p>Напряжение зажигания (и гашения) неоновой лампы, $U_з = 156 \text{ В}$</p><p>Действующее (эффективное) напряжение в сети, $U_{действ} = 220 \text{ В}$</p><p>Частота переменного тока в сети, $\nu = 50 \text{ Гц}$</p><p>Все величины представлены в системе СИ.</p><p><strong>Найти:</strong></p><p><strong>1.</strong> Частоту вспышек лампы, $n$</p><p><strong>2.</strong> Часть периода, в течение которой лампа горит, $\frac{\Delta t_{общ}}{T}$</p><p><strong>Решение:</strong></p><p><strong>Частота n вспышек лампы</strong></p><p>Напряжение в сети изменяется по синусоидальному закону. Неоновая лампа загорается, когда мгновенное значение напряжения по модулю становится равным или превышает напряжение зажигания $|u(t)| \ge U_з$.</p><p>За один период $T$ переменного тока напряжение дважды достигает значений, достаточных для зажигания лампы: один раз в положительной полуволне и один раз в отрицательной. Следовательно, за один период колебаний напряжения в сети лампа вспыхивает дважды. Это означает, что частота вспышек лампы $n$ в два раза больше частоты переменного тока $\nu$.</p><p>$n = 2\nu = 2 \cdot 50 \text{ Гц} = 100 \text{ Гц} = 100 \text{ с}^{-1}$</p><p><strong>Ответ:</strong> $n = 100 \text{ с}^{-1}$.</p><p><strong>В течение какой части периода лампа горит?</strong></p><p>Мгновенное значение напряжения в сети описывается уравнением $u(t) = U_м \sin(\omega t)$, где $U_м$ — амплитудное значение напряжения, а $\omega$ — циклическая частота.</p><p>Амплитудное напряжение связано с действующим напряжением соотношением:</p><p>$U_м = U_{действ} \cdot \sqrt{2} = 220 \cdot \sqrt{2} \approx 311 \text{ В}$</p><p>Лампа горит, когда $|u(t)| \ge U_з$, то есть $|U_м \sin(\omega t)| \ge U_з$.</p><p>Рассмотрим первую положительную полуволну ($0 \le t \le T/2$). Лампа зажжется в момент времени $t_1$, когда $u(t_1) = U_з$, и погаснет в момент $t_2$, когда напряжение снова станет равным $U_з$.</p><p>$U_з = U_м \sin(\omega t_1)$</p><p>Отсюда фаза зажигания: $\omega t_1 = \arcsin\left(\frac{U_з}{U_м}\right)$.</p><p>Из симметрии синусоиды относительно момента времени $t = T/4$ (когда напряжение максимально), момент погасания $t_2$ можно найти как $t_2 = T/2 - t_1$.</p><p>Длительность одной вспышки в положительной полуволне: $\Delta t_1 = t_2 - t_1 = (T/2 - t_1) - t_1 = T/2 - 2t_1$.</p><p>Так как $\omega = \frac{2\pi}{T}$, то $t_1 = \frac{1}{\omega}\arcsin\left(\frac{U_з}{U_м}\right) = \frac{T}{2\pi}\arcsin\left(\frac{U_з}{U_м}\right)$.</p><p>Подставим $t_1$ в выражение для $\Delta t_1$:</p><p>$\Delta t_1 = \frac{T}{2} - 2 \cdot \frac{T}{2\pi}\arcsin\left(\frac{U_з}{U_м}\right) = \frac{T}{2} - \frac{T}{\pi}\arcsin\left(\frac{U_з}{U_м}\right)$</p><p>Поскольку за один период происходит две одинаковые по длительности вспышки (в положительной и отрицательной полуволнах), общая длительность горения лампы за период $T$ равна $\Delta t_{общ} = 2\Delta t_1$.</p><p>$\Delta t_{общ} = 2 \left( \frac{T}{2} - \frac{T}{\pi}\arcsin\left(\frac{U_з}{U_м}\right) \right) = T - \frac{2T}{\pi}\arcsin\left(\frac{U_з}{U_м}\right)$</p><p>Чтобы найти, какую часть периода лампа горит, разделим $\Delta t_{общ}$ на $T$:</p><p>$\frac{\Delta t_{общ}}{T} = 1 - \frac{2}{\pi}\arcsin\left(\frac{U_з}{U_м}\right)$</p><p>Подставим числовые значения (аргумент арксинуса вычисляется в радианах):</p><p>$\frac{\Delta t_{общ}}{T} = 1 - \frac{2}{\pi}\arcsin\left(\frac{156}{311}\right) \approx 1 - \frac{2}{3.1416}\arcsin(0.5016) \approx 1 - 0.6366 \cdot 0.5253 \approx 1 - 0.3344 \approx 0.6656$</p><p>Это значение близко к $2/3 \approx 0.667$.</p><p><strong>Ответ:</strong> лампа горит в течение $0.67$ периода (или примерно $2/3$ периода).</p>"
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№138 (с. 244)
Условие. №138 (с. 244)
скриншот условия
Физика, 10-11 класс Задачник, авторы: Гельфгат Илья Маркович, Генденштейн Лев Элевич, Кирик Леонид Анатольевич, издательство Илекса, Москва, 2008, красного цвета, страница 244, номер 138, Условие

O38. Неоновая лампа с напряжением зажигания $U_3 = 156$ В включена в сеть 220 В, 50 Гц. Найдите частоту $\text{n}$ вспышек лампы. В течение какой части периода лампа горит? Напряжение гашения лампы считайте равным напряжению зажигания.

☑ $n = 100 \text{ с}^{}$; лампа горит 2/3 периода.

Решение. Выберем начало отсчета времени так, чтобы напряжение в сети изменялось по закону $u = U_M \sin\omega t$, где $U_M = \sqrt{2} \cdot 220 \text{ (В)} = 311 \text{ (В)}$. Неоновая лампа горит, когда $|u| \geq U_3$ (на рисунке соответствующие промежутки времени выделены). За период происходят две вспышки, поэтому $n = 100 \text{ с}^{}$. Продолжительность каждой вспышки равна $\Delta t = t_2 - t_1 = \frac{T}{2} - \frac{T}{\pi} \arcsin \frac{U_3}{U_M}$, т. е. лампа горит в течение доли периода $\frac{2\Delta t}{T} = 1 - \frac{2}{\pi} \arcsin \frac{U_3}{U_M} = 0,67$.

Решение. №138 (с. 244)

Дано:

Напряжение зажигания (и гашения) неоновой лампы, $U_з = 156 \text{ В}$

Действующее (эффективное) напряжение в сети, $U_{действ} = 220 \text{ В}$

Частота переменного тока в сети, $\nu = 50 \text{ Гц}$

Все величины представлены в системе СИ.

Найти:

1. Частоту вспышек лампы, $n$

2. Часть периода, в течение которой лампа горит, $\frac{\Delta t_{общ}}{T}$

Решение:

Частота n вспышек лампы

Напряжение в сети изменяется по синусоидальному закону. Неоновая лампа загорается, когда мгновенное значение напряжения по модулю становится равным или превышает напряжение зажигания $|u(t)| \ge U_з$.

За один период $T$ переменного тока напряжение дважды достигает значений, достаточных для зажигания лампы: один раз в положительной полуволне и один раз в отрицательной. Следовательно, за один период колебаний напряжения в сети лампа вспыхивает дважды. Это означает, что частота вспышек лампы $n$ в два раза больше частоты переменного тока $\nu$.

$n = 2\nu = 2 \cdot 50 \text{ Гц} = 100 \text{ Гц} = 100 \text{ с}^{-1}$

Ответ: $n = 100 \text{ с}^{-1}$.

В течение какой части периода лампа горит?

Мгновенное значение напряжения в сети описывается уравнением $u(t) = U_м \sin(\omega t)$, где $U_м$ — амплитудное значение напряжения, а $\omega$ — циклическая частота.

Амплитудное напряжение связано с действующим напряжением соотношением:

$U_м = U_{действ} \cdot \sqrt{2} = 220 \cdot \sqrt{2} \approx 311 \text{ В}$

Лампа горит, когда $|u(t)| \ge U_з$, то есть $|U_м \sin(\omega t)| \ge U_з$.

Рассмотрим первую положительную полуволну ($0 \le t \le T/2$). Лампа зажжется в момент времени $t_1$, когда $u(t_1) = U_з$, и погаснет в момент $t_2$, когда напряжение снова станет равным $U_з$.

$U_з = U_м \sin(\omega t_1)$

Отсюда фаза зажигания: $\omega t_1 = \arcsin\left(\frac{U_з}{U_м}\right)$.

Из симметрии синусоиды относительно момента времени $t = T/4$ (когда напряжение максимально), момент погасания $t_2$ можно найти как $t_2 = T/2 - t_1$.

Длительность одной вспышки в положительной полуволне: $\Delta t_1 = t_2 - t_1 = (T/2 - t_1) - t_1 = T/2 - 2t_1$.

Так как $\omega = \frac{2\pi}{T}$, то $t_1 = \frac{1}{\omega}\arcsin\left(\frac{U_з}{U_м}\right) = \frac{T}{2\pi}\arcsin\left(\frac{U_з}{U_м}\right)$.

Подставим $t_1$ в выражение для $\Delta t_1$:

$\Delta t_1 = \frac{T}{2} - 2 \cdot \frac{T}{2\pi}\arcsin\left(\frac{U_з}{U_м}\right) = \frac{T}{2} - \frac{T}{\pi}\arcsin\left(\frac{U_з}{U_м}\right)$

Поскольку за один период происходит две одинаковые по длительности вспышки (в положительной и отрицательной полуволнах), общая длительность горения лампы за период $T$ равна $\Delta t_{общ} = 2\Delta t_1$.

$\Delta t_{общ} = 2 \left( \frac{T}{2} - \frac{T}{\pi}\arcsin\left(\frac{U_з}{U_м}\right) \right) = T - \frac{2T}{\pi}\arcsin\left(\frac{U_з}{U_м}\right)$

Чтобы найти, какую часть периода лампа горит, разделим $\Delta t_{общ}$ на $T$:

$\frac{\Delta t_{общ}}{T} = 1 - \frac{2}{\pi}\arcsin\left(\frac{U_з}{U_м}\right)$

Подставим числовые значения (аргумент арксинуса вычисляется в радианах):

$\frac{\Delta t_{общ}}{T} = 1 - \frac{2}{\pi}\arcsin\left(\frac{156}{311}\right) \approx 1 - \frac{2}{3.1416}\arcsin(0.5016) \approx 1 - 0.6366 \cdot 0.5253 \approx 1 - 0.3344 \approx 0.6656$

Это значение близко к $2/3 \approx 0.667$.

Ответ: лампа горит в течение $0.67$ периода (или примерно $2/3$ периода).

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