Question

What is the power of a convex lens of focal length 0.5 m?

Answer 1

1. The power of a lens is its ability to converge or diverge the rays of light falling on it.
2. The power of a lens is equal to the reciprocal of the focal length of the lens. The focal length must be in meters. $P=\frac{1}{f}$
3. From the question putting the value of focal length we get $P=\frac{1}{0.5}=2D$
4. SI unit of power is dioptre (D).