Question

A concave lens of focal length 15 cm forms an image of 10 cm from the lens. How far is
the object placed from the lens? Draw the ray diagram.
(PBQ
Focal length. f = -15 cm
If is-ve for a concave lens)​

Answer 1

Answer:

given:

1/f=1/-15

1/u=1/10

to find:

1/v=?

formula:

1/f=1/v-1/u

solution:

1/-15=1/v-1/10

-1/v=1/15-1/10

cross multiply

-1/v=10-15/150

-1/v=-5/150

both side (-) gets cut

1/v=1/30

v=30

Answer 2

Hey You ❤

Your Answer :--

Given :

Focal length of concave lens, f = - 15 cm

Image distance, v= - 10 cm

Lens Formula :

According to the lens formula,

1/v - 1/u = 1/f

1/u = 1/v - 1/f

1/u = -1/10 - ( -1/15)

1/u = -1/10 + 1/15 = -5/150

u = - 30 cm

The negative value of u indicates that the object is placed 30 cm in front of the lens.

Note : For Ray Diagram please see attached file :)

Glad To Help :D

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