Номер 12, страница 9 - гдз по физике 8 класс учебник Изергин

Физика, 8 класс Учебник, автор: Изергин Эдуард Тимофеевич, издательство Русское слово, Москва, 2019

Авторы: Изергин Э. Т.

Тип: Учебник

Издательство: Русское слово

Год издания: 2019 - 2026

Цвет обложки: синий

ISBN: 978-5-533-01067-2

Глава I. Тепловые явления. Параграф 1. Внутренняя энергия - номер 12, страница 9.

App\Models\Task {#1024 // resources/views/models/task/default.blade.php
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  #table: "tasks"
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  #keyType: "int"
  +incrementing: true
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    "field_display_title" => "12"
    "field_outside_task" => null
    "field_task_type" => Illuminate\Database\Eloquent\Collection {#331
      #items: array:1 [
        0 => App\Models\Term {#1029
          #connection: "mysql"
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            "field_cases" => array:6 [
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              "field_genitive_case" => "номера"
              "field_nominative_case" => "номер"
              "field_prepositional_case" => "номере"
            ]
            "field_short_name" => ""
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          #table: "branches"
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                  #connection: "mysql"
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                       …2
                    ]
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            "text" => "<p><strong>Экспериментальное задание 1: Определение фокусного расстояния собирающей линзы</strong></p><p><strong>Цель работы:</strong> Экспериментально определить фокусное расстояние собирающей линзы.</p><p><strong>Оборудование:</strong> собирающая линза, экран, источник света (предмет), линейка или оптическая скамья.</p><p><strong>Краткое теоретическое обоснование и описание эксперимента:</strong></p><p>Для определения фокусного расстояния собирающей линзы используется формула тонкой линзы, которая связывает расстояние от предмета до линзы $\text{d}$, расстояние от линзы до изображения $f'$ и фокусное расстояние линзы $\text{F}$:</p><p>$ \frac{1}{F} = \frac{1}{d} + \frac{1}{f'} $</p><p>В ходе эксперимента на оптической скамье размещают источник света (предмет), собирающую линзу и экран. Устанавливая предмет на различных расстояниях $\text{d}$ от линзы, получают его чёткое действительное изображение на экране. Для каждого положения измеряют расстояние $\text{d}$ и соответствующее ему расстояние $f'$. Проводят серию из нескольких измерений для повышения точности результата. На основе полученных данных производятся вычисления.</p><p>Ниже представлен расчёт на основе гипотетических экспериментальных данных.</p><p><strong>Дано:</strong></p><p>Результаты трёх измерений расстояния от предмета до линзы ($\text{d}$) и от линзы до изображения ($f'$):</p><p>Опыт 1: $d_1 = 25,0$ см, $f'_1 = 37,8$ см</p><p>Опыт 2: $d_2 = 30,0$ см, $f'_2 = 30,2$ см</p><p>Опыт 3: $d_3 = 40,0$ см, $f'_3 = 23,8$ см</p><p>Перевод в систему СИ:</p><p>$d_1 = 0,250$ м, $f'_1 = 0,378$ м</p><p>$d_2 = 0,300$ м, $f'_2 = 0,302$ м</p><p>$d_3 = 0,400$ м, $f'_3 = 0,238$ м</p><p>Приборная погрешность измерения расстояний (цена деления линейки 1 мм) $\Delta d_{приб} = \Delta f'_{приб} = 0,1$ см $= 0,001$ м.</p><p><strong>Найти:</strong></p><p>Фокусное расстояние линзы $\text{F}$ и его погрешность $\Delta F$.</p><p><strong>Решение:</strong></p><p>Для определения фокусного расстояния собирающей линзы воспользуемся формулой тонкой линзы, выразив из неё $\text{F}$:</p><p>$ F = \frac{d \cdot f'}{d + f'} $</p><p><strong>1.</strong> Вычисление фокусного расстояния для каждого опыта:</p><p><strong>Опыт 1:</strong></p><p>$ F_1 = \frac{d_1 \cdot f'_1}{d_1 + f'_1} = \frac{0,250 \cdot 0,378}{0,250 + 0,378} = \frac{0,0945}{0,628} \approx 0,1505 $ м</p><p><strong>Опыт 2:</strong></p><p>$ F_2 = \frac{d_2 \cdot f'_2}{d_2 + f'_2} = \frac{0,300 \cdot 0,302}{0,300 + 0,302} = \frac{0,0906}{0,602} \approx 0,1505 $ м</p><p><strong>Опыт 3:</strong></p><p>$ F_3 = \frac{d_3 \cdot f'_3}{d_3 + f'_3} = \frac{0,400 \cdot 0,238}{0,400 + 0,238} = \frac{0,0952}{0,638} \approx 0,1492 $ м</p><p><strong>2.</strong> Вычисление среднего значения фокусного расстояния:</p><p>$ F_{ср} = \frac{F_1 + F_2 + F_3}{3} = \frac{0,1505 + 0,1505 + 0,1492}{3} = \frac{0,4502}{3} \approx 0,1501 $ м</p><p><strong>3.</strong> Расчёт абсолютной погрешности измерений:</p><p>Найдём абсолютные отклонения для каждого измерения (случайная погрешность):</p><p>$ \Delta F_1 = |F_{ср} - F_1| = |0,1501 - 0,1505| = 0,0004 $ м</p><p>$ \Delta F_2 = |F_{ср} - F_2| = |0,1501 - 0,1505| = 0,0004 $ м</p><p>$ \Delta F_3 = |F_{ср} - F_3| = |0,1501 - 0,1492| = 0,0009 $ м</p><p>Средняя абсолютная случайная погрешность:</p><p>$ \Delta F_{случ} = \frac{\Delta F_1 + \Delta F_2 + \Delta F_3}{3} = \frac{0,0004 + 0,0004 + 0,0009}{3} \approx 0,0006 $ м</p><p>Оценим приборную погрешность для второго опыта (как наиболее близкого к случаю $d=f'=2F$, где погрешность минимальна):</p><p>$ \Delta F_{приб} = F_{ср}^2 \left( \frac{\Delta d_{приб}}{d_2^2} + \frac{\Delta f'_{приб}}{(f'_2)^2} \right) \approx (0,1501)^2 \left( \frac{0,001}{(0,300)^2} + \frac{0,001}{(0,302)^2} \right) \approx 0,0225 \left( 0,0111 + 0,0110 \right) \approx 0,0005 $ м</p><p>Полная абсолютная погрешность равна сумме случайной и приборной погрешностей:</p><p>$ \Delta F = \Delta F_{случ} + \Delta F_{приб} \approx 0,0006 + 0,0005 = 0,0011 $ м</p><p>Округлим погрешность до одной значащей цифры: $ \Delta F \approx 0,001 $ м. Тогда результат для среднего значения фокусного расстояния округляем до того же десятичного знака:</p><p>$ F_{ср} = 0,150 $ м</p><p>Окончательный результат запишем в виде $ F = F_{ср} \pm \Delta F $:</p><p>$ F = (0,150 \pm 0,001) $ м, или $ F = (15,0 \pm 0,1) $ см.</p><p><strong>4.</strong> Расчёт относительной погрешности:</p><p>$ \varepsilon = \frac{\Delta F}{F_{ср}} \cdot 100\% = \frac{0,001}{0,150} \cdot 100\% \approx 0,7\% $</p><p>Так как относительная погрешность мала, результат можно считать достоверным.</p><p><strong>Ответ:</strong> Фокусное расстояние линзы, определённое экспериментально, составляет $ F = (15,0 \pm 0,1) $ см. Относительная погрешность измерений составила примерно $0,7\%$.</p>"
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            "text" => "<p><strong>Экспериментальное задание 1: Определение фокусного расстояния собирающей линзы</strong></p><p><strong>Цель работы:</strong> Экспериментально определить фокусное расстояние собирающей линзы.</p><p><strong>Оборудование:</strong> собирающая линза, экран, источник света (предмет), линейка или оптическая скамья.</p><p><strong>Краткое теоретическое обоснование и описание эксперимента:</strong></p><p>Для определения фокусного расстояния собирающей линзы используется формула тонкой линзы, которая связывает расстояние от предмета до линзы $\text{d}$, расстояние от линзы до изображения $f'$ и фокусное расстояние линзы $\text{F}$:</p><p>$ \frac{1}{F} = \frac{1}{d} + \frac{1}{f'} $</p><p>В ходе эксперимента на оптической скамье размещают источник света (предмет), собирающую линзу и экран. Устанавливая предмет на различных расстояниях $\text{d}$ от линзы, получают его чёткое действительное изображение на экране. Для каждого положения измеряют расстояние $\text{d}$ и соответствующее ему расстояние $f'$. Проводят серию из нескольких измерений для повышения точности результата. На основе полученных данных производятся вычисления.</p><p>Ниже представлен расчёт на основе гипотетических экспериментальных данных.</p><p><strong>Дано:</strong></p><p>Результаты трёх измерений расстояния от предмета до линзы ($\text{d}$) и от линзы до изображения ($f'$):</p><p>Опыт 1: $d_1 = 25,0$ см, $f'_1 = 37,8$ см</p><p>Опыт 2: $d_2 = 30,0$ см, $f'_2 = 30,2$ см</p><p>Опыт 3: $d_3 = 40,0$ см, $f'_3 = 23,8$ см</p><p>Перевод в систему СИ:</p><p>$d_1 = 0,250$ м, $f'_1 = 0,378$ м</p><p>$d_2 = 0,300$ м, $f'_2 = 0,302$ м</p><p>$d_3 = 0,400$ м, $f'_3 = 0,238$ м</p><p>Приборная погрешность измерения расстояний (цена деления линейки 1 мм) $\Delta d_{приб} = \Delta f'_{приб} = 0,1$ см $= 0,001$ м.</p><p><strong>Найти:</strong></p><p>Фокусное расстояние линзы $\text{F}$ и его погрешность $\Delta F$.</p><p><strong>Решение:</strong></p><p>Для определения фокусного расстояния собирающей линзы воспользуемся формулой тонкой линзы, выразив из неё $\text{F}$:</p><p>$ F = \frac{d \cdot f'}{d + f'} $</p><p><strong>1.</strong> Вычисление фокусного расстояния для каждого опыта:</p><p><strong>Опыт 1:</strong></p><p>$ F_1 = \frac{d_1 \cdot f'_1}{d_1 + f'_1} = \frac{0,250 \cdot 0,378}{0,250 + 0,378} = \frac{0,0945}{0,628} \approx 0,1505 $ м</p><p><strong>Опыт 2:</strong></p><p>$ F_2 = \frac{d_2 \cdot f'_2}{d_2 + f'_2} = \frac{0,300 \cdot 0,302}{0,300 + 0,302} = \frac{0,0906}{0,602} \approx 0,1505 $ м</p><p><strong>Опыт 3:</strong></p><p>$ F_3 = \frac{d_3 \cdot f'_3}{d_3 + f'_3} = \frac{0,400 \cdot 0,238}{0,400 + 0,238} = \frac{0,0952}{0,638} \approx 0,1492 $ м</p><p><strong>2.</strong> Вычисление среднего значения фокусного расстояния:</p><p>$ F_{ср} = \frac{F_1 + F_2 + F_3}{3} = \frac{0,1505 + 0,1505 + 0,1492}{3} = \frac{0,4502}{3} \approx 0,1501 $ м</p><p><strong>3.</strong> Расчёт абсолютной погрешности измерений:</p><p>Найдём абсолютные отклонения для каждого измерения (случайная погрешность):</p><p>$ \Delta F_1 = |F_{ср} - F_1| = |0,1501 - 0,1505| = 0,0004 $ м</p><p>$ \Delta F_2 = |F_{ср} - F_2| = |0,1501 - 0,1505| = 0,0004 $ м</p><p>$ \Delta F_3 = |F_{ср} - F_3| = |0,1501 - 0,1492| = 0,0009 $ м</p><p>Средняя абсолютная случайная погрешность:</p><p>$ \Delta F_{случ} = \frac{\Delta F_1 + \Delta F_2 + \Delta F_3}{3} = \frac{0,0004 + 0,0004 + 0,0009}{3} \approx 0,0006 $ м</p><p>Оценим приборную погрешность для второго опыта (как наиболее близкого к случаю $d=f'=2F$, где погрешность минимальна):</p><p>$ \Delta F_{приб} = F_{ср}^2 \left( \frac{\Delta d_{приб}}{d_2^2} + \frac{\Delta f'_{приб}}{(f'_2)^2} \right) \approx (0,1501)^2 \left( \frac{0,001}{(0,300)^2} + \frac{0,001}{(0,302)^2} \right) \approx 0,0225 \left( 0,0111 + 0,0110 \right) \approx 0,0005 $ м</p><p>Полная абсолютная погрешность равна сумме случайной и приборной погрешностей:</p><p>$ \Delta F = \Delta F_{случ} + \Delta F_{приб} \approx 0,0006 + 0,0005 = 0,0011 $ м</p><p>Округлим погрешность до одной значащей цифры: $ \Delta F \approx 0,001 $ м. Тогда результат для среднего значения фокусного расстояния округляем до того же десятичного знака:</p><p>$ F_{ср} = 0,150 $ м</p><p>Окончательный результат запишем в виде $ F = F_{ср} \pm \Delta F $:</p><p>$ F = (0,150 \pm 0,001) $ м, или $ F = (15,0 \pm 0,1) $ см.</p><p><strong>4.</strong> Расчёт относительной погрешности:</p><p>$ \varepsilon = \frac{\Delta F}{F_{ср}} \cdot 100\% = \frac{0,001}{0,150} \cdot 100\% \approx 0,7\% $</p><p>Так как относительная погрешность мала, результат можно считать достоверным.</p><p><strong>Ответ:</strong> Фокусное расстояние линзы, определённое экспериментально, составляет $ F = (15,0 \pm 0,1) $ см. Относительная погрешность измерений составила примерно $0,7\%$.</p>"
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    "page" => Illuminate\Database\Eloquent\Collection {#1512
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                0 => App\Models\Element {#1213
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            "tasks" => Illuminate\Database\Eloquent\Collection {#1221
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                0 => App\Models\Task {#1222
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                    0 => "*"
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                }
                1 => App\Models\Task {#1378
                  #connection: "mysql"
                  #table: "tasks"
                  #primaryKey: "id"
                  #keyType: "int"
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                    "created_at" => "2026-04-10 13:58:26"
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                    "field_task_type" => Illuminate\Database\Eloquent\Collection {#1379 …2}
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                }
                2 => App\Models\Task {#1401
                  #connection: "mysql"
                  #table: "tasks"
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                    "created_at" => "2026-04-10 13:58:26"
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                    "field_task_type" => Illuminate\Database\Eloquent\Collection {#1402 …2}
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                    0 => "*"
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                }
                3 => App\Models\Task {#1424
                  #connection: "mysql"
                  #table: "tasks"
                  #primaryKey: "id"
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                  #attributes: array:24 [
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                    "field_task_type" => Illuminate\Database\Eloquent\Collection {#1425 …2}
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                    "parent_branches" => Illuminate\Database\Eloquent\Collection {#1428 …2}
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                    "book" => Illuminate\Database\Eloquent\Collection {#1446 …2}
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                }
                4 => App\Models\Task {#1447
                  #connection: "mysql"
                  #table: "tasks"
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                    "created_at" => "2026-04-10 13:58:26"
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                    "field_display_title" => "10"
                    "field_outside_task" => null
                    "field_task_type" => Illuminate\Database\Eloquent\Collection {#1448 …2}
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                    "book" => Illuminate\Database\Eloquent\Collection {#1463 …2}
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                    0 => "*"
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                }
                5 => App\Models\Task {#1464
                  #connection: "mysql"
                  #table: "tasks"
                  #primaryKey: "id"
                  #keyType: "int"
                  +incrementing: true
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                    "created_at" => "2026-04-10 13:58:26"
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                    "field_url" => "/8-klass/fizika/izergin-uchebnik/01-11"
                    "field_display_title" => "11"
                    "field_outside_task" => null
                    "field_task_type" => Illuminate\Database\Eloquent\Collection {#1465 …2}
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                    "edition_groups" => Illuminate\Database\Eloquent\Collection {#1466 …2}
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                    "parent_branches" => Illuminate\Database\Eloquent\Collection {#1468 …2}
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                    0 => "*"
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                }
                6 => App\Models\Task {#1487
                  #connection: "mysql"
                  #table: "tasks"
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                    "field_task_type" => Illuminate\Database\Eloquent\Collection {#1488 …2}
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№12 (с. 9)
Условие. №12 (с. 9)
скриншот условия
Физика, 8 класс Учебник, автор: Изергин Эдуард Тимофеевич, издательство Русское слово, Москва, 2019, страница 9, номер 12, Условие

12*. Выполните экспериментальное задание 1 на с. 249.

Решение. №12 (с. 9)

Экспериментальное задание 1: Определение фокусного расстояния собирающей линзы

Цель работы: Экспериментально определить фокусное расстояние собирающей линзы.

Оборудование: собирающая линза, экран, источник света (предмет), линейка или оптическая скамья.

Краткое теоретическое обоснование и описание эксперимента:

Для определения фокусного расстояния собирающей линзы используется формула тонкой линзы, которая связывает расстояние от предмета до линзы $\text{d}$, расстояние от линзы до изображения $f'$ и фокусное расстояние линзы $\text{F}$:

$ \frac{1}{F} = \frac{1}{d} + \frac{1}{f'} $

В ходе эксперимента на оптической скамье размещают источник света (предмет), собирающую линзу и экран. Устанавливая предмет на различных расстояниях $\text{d}$ от линзы, получают его чёткое действительное изображение на экране. Для каждого положения измеряют расстояние $\text{d}$ и соответствующее ему расстояние $f'$. Проводят серию из нескольких измерений для повышения точности результата. На основе полученных данных производятся вычисления.

Ниже представлен расчёт на основе гипотетических экспериментальных данных.

Дано:

Результаты трёх измерений расстояния от предмета до линзы ($\text{d}$) и от линзы до изображения ($f'$):

Опыт 1: $d_1 = 25,0$ см, $f'_1 = 37,8$ см

Опыт 2: $d_2 = 30,0$ см, $f'_2 = 30,2$ см

Опыт 3: $d_3 = 40,0$ см, $f'_3 = 23,8$ см

Перевод в систему СИ:

$d_1 = 0,250$ м, $f'_1 = 0,378$ м

$d_2 = 0,300$ м, $f'_2 = 0,302$ м

$d_3 = 0,400$ м, $f'_3 = 0,238$ м

Приборная погрешность измерения расстояний (цена деления линейки 1 мм) $\Delta d_{приб} = \Delta f'_{приб} = 0,1$ см $= 0,001$ м.

Найти:

Фокусное расстояние линзы $\text{F}$ и его погрешность $\Delta F$.

Решение:

Для определения фокусного расстояния собирающей линзы воспользуемся формулой тонкой линзы, выразив из неё $\text{F}$:

$ F = \frac{d \cdot f'}{d + f'} $

1. Вычисление фокусного расстояния для каждого опыта:

Опыт 1:

$ F_1 = \frac{d_1 \cdot f'_1}{d_1 + f'_1} = \frac{0,250 \cdot 0,378}{0,250 + 0,378} = \frac{0,0945}{0,628} \approx 0,1505 $ м

Опыт 2:

$ F_2 = \frac{d_2 \cdot f'_2}{d_2 + f'_2} = \frac{0,300 \cdot 0,302}{0,300 + 0,302} = \frac{0,0906}{0,602} \approx 0,1505 $ м

Опыт 3:

$ F_3 = \frac{d_3 \cdot f'_3}{d_3 + f'_3} = \frac{0,400 \cdot 0,238}{0,400 + 0,238} = \frac{0,0952}{0,638} \approx 0,1492 $ м

2. Вычисление среднего значения фокусного расстояния:

$ F_{ср} = \frac{F_1 + F_2 + F_3}{3} = \frac{0,1505 + 0,1505 + 0,1492}{3} = \frac{0,4502}{3} \approx 0,1501 $ м

3. Расчёт абсолютной погрешности измерений:

Найдём абсолютные отклонения для каждого измерения (случайная погрешность):

$ \Delta F_1 = |F_{ср} - F_1| = |0,1501 - 0,1505| = 0,0004 $ м

$ \Delta F_2 = |F_{ср} - F_2| = |0,1501 - 0,1505| = 0,0004 $ м

$ \Delta F_3 = |F_{ср} - F_3| = |0,1501 - 0,1492| = 0,0009 $ м

Средняя абсолютная случайная погрешность:

$ \Delta F_{случ} = \frac{\Delta F_1 + \Delta F_2 + \Delta F_3}{3} = \frac{0,0004 + 0,0004 + 0,0009}{3} \approx 0,0006 $ м

Оценим приборную погрешность для второго опыта (как наиболее близкого к случаю $d=f'=2F$, где погрешность минимальна):

$ \Delta F_{приб} = F_{ср}^2 \left( \frac{\Delta d_{приб}}{d_2^2} + \frac{\Delta f'_{приб}}{(f'_2)^2} \right) \approx (0,1501)^2 \left( \frac{0,001}{(0,300)^2} + \frac{0,001}{(0,302)^2} \right) \approx 0,0225 \left( 0,0111 + 0,0110 \right) \approx 0,0005 $ м

Полная абсолютная погрешность равна сумме случайной и приборной погрешностей:

$ \Delta F = \Delta F_{случ} + \Delta F_{приб} \approx 0,0006 + 0,0005 = 0,0011 $ м

Округлим погрешность до одной значащей цифры: $ \Delta F \approx 0,001 $ м. Тогда результат для среднего значения фокусного расстояния округляем до того же десятичного знака:

$ F_{ср} = 0,150 $ м

Окончательный результат запишем в виде $ F = F_{ср} \pm \Delta F $:

$ F = (0,150 \pm 0,001) $ м, или $ F = (15,0 \pm 0,1) $ см.

4. Расчёт относительной погрешности:

$ \varepsilon = \frac{\Delta F}{F_{ср}} \cdot 100\% = \frac{0,001}{0,150} \cdot 100\% \approx 0,7\% $

Так как относительная погрешность мала, результат можно считать достоверным.

Ответ: Фокусное расстояние линзы, определённое экспериментально, составляет $ F = (15,0 \pm 0,1) $ см. Относительная погрешность измерений составила примерно $0,7\%$.

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