Question

The focal length of a lens of power +4D will be

(A) +0.50 meter (B) -0.25 meter

(C) +0.25 meter (D) -0.50 meter

Answer 1

Power = 1/f

+4 = 1/f

f = 1/4 = 0.25 m

Answer is C

Answer 2

Heya.........!!!!!

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Given :-

• Power of Lens = + 4 D

We can take out focal Length by applying the formulae

$p \: \: = \frac{1}{f}$

=> 4 = 1/f

=> f = 1/4

=> f = + 0.25 meter.

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