Question

Find the power of a concave lens of 2 m focal length.

Hint:

The power of a lens is measured in diopters (D), with concave lenses having negative power and convex lenses having positive power.

Answer 1

The power (\( P \)) of a lens is given by the formula: \[ P = \frac{1}{f} \quad \text{(in meters)} \] Given \( f = -2 \) m (negative for concave lenses): \[ P = \frac{1}{-2} = -0.5 D \] Final Answer: The power of the concave lens is \(-0.5D\).