A plane concave lens of glass (μ = 1.5) has a radius of curvature of its curved face 50 cm. The power of the lens is:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → -1.0 D
To find the power of the concave lens,
$\frac{1}{f}=(μ-1)\left(\frac{1}{R_1}-\frac{1}{R_2}\right)$ [lens maker formula]
$\frac{1}{f}=(1.5-1)(\frac{1}{50})=\frac{1}{100}$
focal length, $f=-100cm$
∴ Power, $P=\frac{1}{f}=\frac{\frac{1}{100}}{-100}=-1m^{-1}=-1D$