The focal length of a spherical mirror of radius of curvature 30 cm is:(a) 10 cm (b) 15 cm (c) 20 cm (d) 30 cm
(b) 15 cm
Explanation
Given,
Radius of curvature = $r$ = 30 cm
To find = $f$ = Focal length
Solution
We know that the focal length of a spherical mirror is half of its radius of curvature.
Mathematically it is given as-
$f=\frac{1}{2}R$
Now, putting the given value we get-
$f=\frac{1}{2}\times 30$
$f=15cm$
Hence, the focal length of the spherical mirror will be 15cm.
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