Question

(i) What is magnifying glass? State its two uses.

(ii) Write an expression for the magnifying power of a simple microscope. How can it be increased?

Answer 1

(i) Magnifying glass is a convex lens of short focal length. It is mounted in a lens holder for practical use. It is used to see and read the small letters and figures and also used by watchmakers to see the small parts and screws of the watch.

(ii) The magnifying power of the microscope is given as:
Magnifying power M = 1 + D / f
Where f is the focal length of the lens and D is the least distance of distinct vision.
The magnifying power of the microscope be increased by using the lens of short focal length i.e shorter the focal length, more is the magnifying power. But it cannot be increased indefinitely.