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
Answer is (c) A convex lens of focal length 5 cm.
Explanation
A concave lens will always give a diminished image.
So, we use a convex lens as it makes an enlarged image
Now, the smaller the focal length, the greater will be the power of the lens.
Hence, a convex lens of focal length 5cm will be preferable.
