A student measures the focal length of a convex lens by putting an object pin at a distance `u` from the lens and measuring the distance `v` of the image pin. The graph between `u` and `v` plotted by the student should look like

Options

A.
B.
C.
D.

Answer

C

Explanation

In a convex lens, `u` is negative and `v` is positive (expect when image is virtual). As `u` is increased, `v` decreases. Therefore, graph `( c)` is the correct choice in Fig.