Question

A 2mm object is placed 20cm from converging lens of 10cm focal length. The size of its image will be
a. 1mm
b. 2mm
c. 3mm
d. 4mm ​

Answer 1

Explanation:

Given: u=-20 cm f=10 cm (concave lens)

To find : magnification

Solution : From Lens Formula

$= > \frac{1}{v} - \frac{1}{u} = \frac{1}{f}$

$= > \frac{1}{v} + \frac{1}{20} = \frac{1}{10}$

$= > \frac{1}{v} = \frac{1}{10} - \frac{1}{20}$

$= > \frac{1}{v} = \frac{1}{20}$

$= > v = 20cm$

So magnification for a lens is given by

$= > m = \frac{v}{u} = \frac{20}{ - 20} = 1$

$= > m = - 1$

1mm is the correct answer

$\huge{ son \: prodigal}$