Question

 A pin is placed 10 cm in front of a convex lens of focal length 20 cm and made of a material of refractive index 1.5 . The surface of the lens farther away from the pin is silvered and has a radius of curvature of 22 cm . Determine the position of the final image. Is the image real or virtual? 

Answer 1

Since the convex lens with a silvered surface behaves as a concave mirror of effective focal length F , we have F = -110/21 cm and u = - 10 cm.

The negative sign shows that the image is in front of the effective mirror and hence is real.