Light from a point source in the air falls upon a convex refracting surface (refractive index 1.5) A light source is placed at 2 m in front of the surface. If the image is formed 3.5 m from the surface, the radius of curvature of the convex surface is
1
0.539 m
2
0.7 m
3
0.435 m
4
0.876 m