Question

Two convex lenses of same focal length are fixed in a PVC pipe at a distance double to their focal length. What happens if a boy sees the moon with that arrangement?

Answer 1

1. The rays coming from moon are parallel. The first lens converges the rays at focus. 

2. The converging point is the focus of second lens. So the second lens convert the diverging rays into parallel.

3. Hence, in the rays of moon, there will be no change when we see moon with this arrangement or without this arrangement.

(OR)

1. This arrangement does not make any difference in the rays coming from moon. 

2. The moon appears same if we see directly or with this arrangement.