Question

The focal length of a plano convex glass lens is 20 cm the plane face of it is silvered and illuminating object is placed at a distance of 60 centimetre from the lens on its axis on the convex side the distance of the images

Answer 1

Answer:

When plane surface is silvered, light suffers refraction at convex surface, then reflection from plane surface, then reflection from plane surface and final refraction at the curved surface again as shown in Fig. <br>Power of such a lens, <br><br> =<br> New focal length,