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I followed the process to solve this problem from other chegg posts and got 24.6

ID: 2032245 • Letter: I

Question

I followed the process to solve this problem from other chegg posts and got 24.6 mm, but apparently thats wrong.

A. How far from ?41.0-mm-focal-length lens must an object be placed if its image is to be magnified 2.50× and be virtual? Follow the sign conventions.

[Hint: Consider real objects and virtual objects (formed by some other piece of optics).]

B. How far from ?41.0-mm-focal-length lens must an object be placed if its image is to be magnified 2.50× and be real? Follow the sign conventions.
[Hint: Consider real objects and virtual objects (formed by some other piece of optics).]

Explanation / Answer

here,

A)

focal length , f = - 41 mm = 4.1 cm

let the image distance and object distance be di and do

using the lens formula

1/f = 1/di + 1/do

- 1/4.1 = 1/di + 1/do .....(1)

and

magnification , m = - di/do

2.5 = - di/do ...(2)

from (1) and (2)

do = - 2.46 cm

di = 6.15 cm

the object distance is - 2.46 cm

and the image is real