If focal length of a concave lens is 50 cm, then the power of the lens would be
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → -2 D
Given: Focal length, $f = -50 \text{ cm} = -0.5 \text{ m}$
Formula: $P = \frac{1}{f}$
$P = \frac{1}{-0.5} = -2 \, \text{D}$
Therefore, the power of the concave lens is $-2 \, \text{dioptres}$.