Question

the size of a real image by a convex lens is equal to the size of the object. then the focal length of the lens is equal to (a) 1/2 (b) 2u (3)2v (4) v​

Answer 1

Easy ans is 2f

When u place on f distance image will form same as object
So focal lenth will distance of object/2

Answer 2

The focal length of the lens is very large, which corresponds to a very small amount of curvature. Therefore, we can conclude that the correct answer is: (4) v

We can use the thin lens formula to solve this problem:

1/f = 1/v - 1/u

where f is the focal length of the lens, v is the image distance, and u is the object distance.

If the size of the real image is equal to the size of the object, this means that the magnification of the lens is equal to 1. That is:

m = v/u = 1

Therefore, we can simplify the thin lens formula to:

1/f = 1/v - m/u = 1/v - 1/u

Substituting m = 1, we get:

1/f = 1/v - 1/u

Since the size of the real image is equal to the size of the object, we can also use the magnification formula to relate v and u:

m = v/u = 1

Therefore:

v = u

Substituting v = u into the thin lens formula, we get:

1/f = 1/v - 1/v = 0

Simplifying this equation, we get:

f = infinity

This means that the focal length of the lens is very large, which corresponds to a very small amount of curvature.

In other words, the lens is almost flat. Therefore, we can conclude that the correct answer is: (4) v

For similar question on convex lens.

https://brainly.in/question/283608

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