The power of a lens is -2.0 D. Find its focal length and its kind. - Noon Academy

The power of a lens is -2.0 D. Find its focal length and its kind.

Class 10 | ICSE | Physics | Refraction through a Lens | Selina

The power of a lens is -2.0 D. Find its focal length and its kind.

Solution:

According to the question –

The power of a lens is -2.0 D

We know that the expression of Power of a lens is

P = 1 / f

Upon substituting values, we have => -2 = 1 / f

Or, f = 1 / -2 = -0.5 m

Therefore, f = – 50 cm

Since the power is negative it implies that the lens is a concave lens.

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