Magnifying Visors

What power magnifying glass will this lens make?

A magnifying lens focuses the sun's rays to a point 13 cm away from the lens. What power magnifying glass will this lens make?

Public Comments

1. How about doing your own homework on this and the 3 other questions?
2. Since the suns is a source at infinity, the power will be 0.77 D 0.13 cm x (1 m / 10 cm) = 0.13 m Power = 1 / (Focal Length in meters) = 1 / 0.13 m = 0.77 D