Question

Thr power of lens is -2.D. the type of lens and its focal length are respectivelly?

Answer 1

It's a concave lens because it's power is negative.As we know focal length is reciprocal of the power of a lens...
so..Focal length will be:
-0.5 cm(with sign convention)

Answer 2

The focal length of the lens is -50 cm and the lens is concave.

Explanation:

It is given that,

The power of the lens is -2 D. We know that the relation between the power and the focal length is inverse. It is given by :

$f=\dfrac{1}{P}$

P is the power of the lens

$f=\dfrac{1}{-2}$

f = -0.5 m

or

f = -50 cm

So, the focal length of the lens is -50 cm and the lens is concave. Hence, this is the required solution.

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Power of the lens

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