CUET Preparation Today
CUET
Physics
Ray Optics
The power of a convex lens of focal length 20 cm in dioptre unit is
0.5
0.05
5
2.5
The correct answer is Option (3) → 5
f = 20 cm
= 0.2 m
Power of lens is given by
$P=\frac{1}{f}$
$P=\frac{1}{20 ~cm}=\frac{1}{20 \times 10^{-2}}$ dioptre
∴ P = 5D