Question 3
Find the power of a concave lens of focal length 2 m.

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Solution

We know that, focal length is negative for concave lens.
Thus, focal length of the given concave lens, f = -2 m
$∴$ Power of lens,
$P = \frac{1}{f} = \frac{1}{(- 2)} = - 0.5 D$

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Question 3 Find the power of a concave lens of focal length 2 m.

We know that, focal length is negative for concave lens. Thus, focal length of the given concave lens, f = -2 m ∴ Power of lens, P=1f=1(−2)=−0.5 D

Question 3
Find the power of a concave lens of focal length 2 m.

We know that, focal length is negative for concave lens.
Thus, focal length of the given concave lens, f = -2 m
$∴$ Power of lens,
$P = \frac{1}{f} = \frac{1}{(- 2)} = - 0.5 D$