Question

A concave mirror is a part of sphere of radius 40cm . What is the focal length of the mirror

Answer 1

Answer:

it is 20 cm

Explanation:

radius of curvature is twice the focal length of the mirror

radius= 2* focal length

40 =2* focal length

focal length =20cm

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Answer 2

Given,

A concave mirror is a part of sphere.

Radius (R) = 40cm

To Find:-

Focal length of the mirror.

Calculations:-

$\underline{\boxed{\sf{F={\frac{R}{2}}}}}$

F = Focal length

R = Radius

${F={\frac{40}{2}}}$

F=20 cm

So

The focal length of the mirror is 20cm.