Question

An object is placed in front of a lens at 10cm from its optic centre.The image is seen on the same side of lens at 60cm distance.What is the nature and focal length of the lens?

Answer 1

Answer:

Focal length is 12 cm

Nature is Convex lens

Explanation:

Object distance=p= 10 cm

Image distance =q = -60 cm (Image is at the same side)

focal length= f = ?

According to lens equation

1/f = 1/p + 1/q

1/f = 1/10 + 1/(-60)

1/f = 1/10 - 1/60

1/f = 5/60

or

f= 12 cm

(It is a convex lens because focal length is positive)