Question

name the type of lens if it's power is -2OD. find the focal length of this lens
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Answer 1

The type of lens is a concave lens and its focal length is 5 cm.

Explanation:

The type of lens is a concave lens.

We are given that:

The power of lens = - 20 D

As we know that The formula for focal length in case of power is:

f = 1 / P

Now

f = 1 / -20

f = 0.05 m

Now multiply with 100 to convert the unit into cm

f = 0.05 x 100 = 5 cm

Answer 2

Explanation:

its a concave lens because the power is negative