Question

The radius of curvature of a spherical mirror is 20 cm. What is its focal
length?
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Answer 1

Answer:

Radius of curvature, R= 20 cm Radius of curvature of a spherical mirror = 2 � Focal length (f) R= 2f f= R/2 = 20 / 2 = 10 Hence, the focal length of the given spherical mirror is 10 cm.

Explanation:

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Answer 2

Given :-

• Radius of curvature (R) = 20 cm

To find :-

• Focal length = ?

Solution :-

we know that,the focal length of a spherical mirror like a concave mirror or a convex mirror is equal to half of its radius of curvature.

So,

$\orange{\bigstar}\:\:{\underline{\boxed{\bf\pink{f=\dfrac{R}{2}}}}}$

$\rm\longrightarrow\:f=\cancel\dfrac{20}{2}$

$\rm\longrightarrow\:f=10\:cm$

Hence,the focal length of the spherical mirror will be 10 cm.

More Information :-

Focal length of concave mirror : The focal length of a concave mirror is the distance between it's pole and principal focus.

Focal length of convex mirror : The focal length of convex mirror is the distance from the pole to its principal.