The focal length of a spherical mirror of radius of curvature $40 c m$ is

10 c m

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20 c m

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80 c m

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None

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Solution

The correct option is C $20 c m$
We know,
$F o c a l l e n g t h (f) = \frac{R a d i u s o f c u r v a t u r e (R)}{2}$

Given,
Radius of curvature, $R = 40 c m$
$\Rightarrow f = \frac{R}{2} = \frac{40}{2} = 20 c m$

Hence, the correct answer is OPTION B.

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The focal length of a spherical mirror of radius of curvature 40cm is

The correct option is C 20cmWe know,Focal length (f)=Radius of curvature (R)2Given, Radius of curvature, R=40 cm⇒f=R2=402=20 cmHence, the correct answer is OPTION B.

The focal length of a spherical mirror of radius of curvature $40 c m$ is

The correct option is C $20 c m$
We know,
$F o c a l l e n g t h (f) = \frac{R a d i u s o f c u r v a t u r e (R)}{2}$

Given,
Radius of curvature, $R = 40 c m$
$\Rightarrow f = \frac{R}{2} = \frac{40}{2} = 20 c m$

Hence, the correct answer is OPTION B.