Question

A convex lens has a focal length of 10cm is placed at a distance of 12 cm from a wall. How far from the lens should an object be placed

Answer 1

Answer:

Explanation

Focal length of the lens(f) =10cm

The image distance (v)= 12cm

The object distance (u)=?

We know,

1/f = 1/v-1/u

Or, 1/10 =1/12-1/u

Or, 1/10-1/12=-1/u

Or,1/60= -1/u

Or u=60cm(here negative sign shows that the object is kept infront of the lens)

Ans. The object should be kept 60cm infront of the lens.