Question

A convex lens has a focal length of 15 cm. At what distance should the object be placed from the lens so that it forms an image at 10 cm, from the lens. It is a CONVEX LENS .​

Answer 1

Answer:

Object distance, u = -30 cm

Explanation:

Given:

Focal length,f = +15 cm

Image distance,v = 10 cm

To find : Object distance,u

Ans : We know,

1/f = 1/v - 1/u

1/u = 1/f - 1/v

= 1/15 - 1/10

= 2 - 3/30

1/u = -1/30

-u = 30

u = -30

Therefore,

Object distance,u = -30 cm

I hope it helped..!!