Question

A concave lens has focal
length of 15 cm. At what
distance should the object
from the lens be placed so
that it forms an image at 10
cm from the lens?
​

Answer 1

Answer:

Hey there, this is ur answer......

Explanation:

Here, focal length of concave lens, f=-15cm. object distance, u=?, image distance, v=-10cm, magnification of lens, m=? Thus the object should be placed at a distance of 30 cm on the left side of the concave lens.

I hope this is helpful for you..... please MARK as BRAINLIST and FOLLOW me............

Answer 2

Explanation:

Given: Concave lens, f=-15cm, v=-10cm

To find: u=?

Formula:

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

$= > \frac{1}{ - 10} - \frac{1}{u} = \frac{1}{ - 15}$

$= > \frac{1 \times 3}{ - 10 \times 3} + \frac{1 \times 2}{ 15 \times 2} = \frac{1}{u}$

$= > \frac{ - 3}{30} + \frac{2}{30} = \frac{ - 3 + 2}{30} = \frac{ - 1}{30} = \frac{1}{u}$

$u = - 30cm$

The object should be placed at a distance of 30cm from the lens.