Question

A concave lens has a focal length of 20 cm. What is the power of the lens?
A) -5 dioptre
B) -0.05 dioptre
C) 0.05 dioptre
D)5 dioptre

Answer 1

Answer:

P = 5 Dioptres

Explanation:

We know that, Power = 1 ÷ f (in Meters)

20 cm = 0.2 m

Placing the values in the formula we get,

P = 1 ÷ 0.2

P = 5 D

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Answer 2

Answer:

-5 Dioptre

Explanation:

Power of lens is reciprocal of its focal lenght . It is given by : So,the power of a concave lens is-5 Dioptre....

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