Question

Image produced by a convex lens is double that of size of the object find two possible focal length of the lens if the distance of image is 30 cm

Answer 1

Answer:

the focal length is 10cm

Explanation:

the image distance =30cm.

the linear magnification is 2

so, image distance / object distance = 2

or, object distance = 30/2=15 cm

by putting the values in 1/u+1/v=1/f ,we get,

1/15+1/30=1/f

or, 1/f=1/10

or, f=10

the focal length =10cm