Question

The figure shows a convex lens of focal length 30 cm. There is a plane boundary of a medium of refractive index 3/2at a distance of 10 cm from the lens. The distance from the lens at which parallel rays incident on the lens will converge is

Answer 1

The rays will converge at a distance of 40 cm from the lens.

Explanation:

The lens will converge the rays at its focus i.e. 30 cm from the lens or 20 cm from the refracting surface.

PI1 = 20 cm

PI2 = m (PI2)

= 3 / 2 × 20 = 30 cm

So, the rays will converge at a distance of 40 cm from the lens.