Q3 of 25 Page 10

Find the power of a concave lens of focal length 2 m. ( CBSE 2011)

The focal length of a concave lens is considered negative and hence written with a minus sign. So, focal length of concave lens, f = -2 m

Now, Power, P = 


P=
Thus, Power, P = -0.5D, Where D stands for Dioptre

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