Question

find the focal length of a lens of power 2D
a)50m
b)5cm
c)50cm
d)5m​

Answer 1

Option C) 50 cm (or 1/2 m).

EXPLANATION :-

relation between focal length [f] and power [p] of the lens is given by,

$p = \frac{1}{f} \\ \\ or \: 2 = \frac{1}{f} \\ \\ or \: f = \frac{1}{2} \: \: m \\ \\ orf = 50cm$

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