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  • An experiment is conducted to determine the focal length of a convex lens. An object is placed at a known distance from the lens, and its image is formed on a screen. The object distance <img

An experiment is conducted to determine the focal length of a convex lens. An object is placed at a known distance from the lens, and its image is formed on a screen. The object distance (u) is 30\ cm, and the image distance (v) is 60\ cm. Calculate the focal length (f) of the convex lens.

Option: 1

30\ cm


Option: 2

20\ cm


Option: 3

-20\ cm


Option: 4

-30\ cm


Answers (1)

best_answer

Given values:

  • Object distance (u)=30\ cm
  • Image distance (v) = 60 \ cm

The lens formula relates the object distance, image distance, and focal
length:

\frac{1}{f}=-\frac{1}{u}+\frac{1}{v}

Solve for f:

f=-\frac{1}{\frac{1}{u}+\frac{1}{v}}
Substitute the given values and calculate f:

f=-\frac{1}{\frac{1}{-30 \mathrm{~cm}}+\frac{1}{60 \mathrm{~cm}}}

The focal length (f) of the convex lens is calculated using the above formula.
f= 20 \ cm
So, correct option is B

Posted by

Divya Prakash Singh

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