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CBSE Class 10 Science Question 31 of 31

Light - Reflection and Refraction — Question 3

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Question

Question 3

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

Answer

Given,

focal length (f) = -2 m [∵ focal length of concave lens is negative]

Power of lens (P) = 1f(in metres)\dfrac{1}{f \text{(in metres)}}

Hence, P = 1f\dfrac{1}{\text{f}} = 1-2\dfrac{1}{\text{-2}} = -0.5 D