Question

2.
What is the power of a concave lens of
focal length 25 cm ?
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Answer 1

Answer:-4D

Explanation:

P=1/f(in meter)

=100/-25=-4D

Answer 2

Answer:

Focal length of a concave lens is always negative.

So f=(-25)cm

Power=1/f

=1/(-0.25)= (-4)D

Power= (-4)D