WBJEE · Physics · Ray Optics
A plano-concave lens is made of glass of refractive index 1.5 and the radius of curvature of its curved face is \(100 \mathrm{~cm}\). What is the power of the lens?
- A \(+0.5 \mathrm{D}\)
- B \(-0.5 \mathrm{D}\)
- C \(-2 \mathrm{D}\)
- D \(+2 \mathrm{D}\)
Answer & Solution
Correct Answer
(B) \(-0.5 \mathrm{D}\)
Step-by-step Solution
Detailed explanation
\(\begin{aligned} & \text {Hints: } P=\frac{1}{f}=(\mu-1)\left(\frac{1}{R_1}-\frac{1}{R_2}\right) \\ & =(1.5-1)\left(\frac{1}{\infty}-\frac{1}{1 \mathrm{~m}}\right) \\ & =0.5(-1) \\ & P=-0.5 \mathrm{D} \end{aligned}\)
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