Question

Which of the following lenses would you prefer to use while reading small letters found in a dictionary?
(a) A convex lens of focal length 50 cm.
(b) A concave lens of focal length 50 cm.
(c) A convex lens of focal length 5 cm.
(d) A concave lens of focal length 5 cm.

Answer 1

it is best to use a convex lens of focal length 5 cm

Answer 2

(c) A convex lens of focal length 5 cm.

The convex lens gives magnified image of an placed the curvature and focal length for for convex lenses having shorter focal length.

The magnification is more for convex the more lenses having shorter focal length and reading small letters form the convex lens of focal length 5 cm should be used.