Question

ДАЮ 15 БАЛЛОВ На стене получается четкое изображение, если расположить светящийся экран мобильного телефона на расстоянии 40 см от стены и ровно посередине между телефоном и стеной поставить собирающую линзу. Каково фокусное расстояние этой линзы?

Answer 1

Ответ:

10 см

Объяснение:

Собирающая линза даёт четкое перевёрнутое изображение на удвоенном фокусном расстоянии. А если 2f = 20 см (линза посередине между экраном и стеной), то f = 20 см / 2 = 10 см

Answer 2

Calculation of the focal length of a lens

To determine the focal length of a lens in this scenario, we can use the lens formula:

1/f = 1/v - 1/u

Where: - f is the focal length of the lens - v is the image distance (distance between the lens and the image formed on the wall) - u is the object distance (distance between the lens and the object, which is the screen of the mobile phone)

In this case, the object distance (u) is 40 cm, and the image distance (v) is also 40 cm since the image is formed on the wall. Plugging these values into the lens formula, we can solve for the focal length (f).

1/f = 1/40 - 1/40

Simplifying the equation:

1/f = 0

Since the right side of the equation is zero, the left side must also be zero. Therefore, the focal length (f) of the lens in this scenario is undefined.

Please note that this result is based on the information provided and assumes ideal conditions. In practice, there may be other factors that could affect the image formation and the determination of the focal length.