Question

To find focal length of concave lens using convex lens of rough focal length 20 readings

Answer 1

f= R/2
R= 2×20=40cm
soR=40cm

Answer 2

Answer:

To determine focal length of a convex lens

Place the holder with the screen on the bench. The position of the screen should be such that the sharp image of the distant object is obtained on it. The difference between the position of the lens and the screen is equal to the focal length of the given convex lens.