If the radius of curvature of a concave mirror is 20 cm, then focal length of the mirror will be
(a) 20 cm
(b) 15 cm
(c) 10 cm
(d) 40 cm
WBBSE
Class X
Physical Science
Light – Reflection and Refraction
01 Mark
2022
(c) 10 cm
Explanation: The focal length (f) of a concave mirror is half of its radius of curvature (R).
So, f = 20\over2 = 10 cm
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