The power of the lens is +2.5D. What is the radius of the curvature?

A. 2.5 cm
B. 25.0 cm
C. 40.0 cm
D. 80.0 cm

Correct Answer:

Option D = 80.0 cm

Explanation

The power of a lens is defined as the reciprocal of its focal length in metres:

P = 100/f → 2.5 = 100/f
where P is the power in diopters and f is the focal length in metres.

2.5 * f = 100

f = 100/2.5
f = 40

Where f = r/2
radius of the curvature[r] = f * 2 → 40 * 2

r = 80cm