Question

The nature of the image of a candle flame located 40 cm away from a concave mirror is real, inverted, and magnified four times. What is the radius of curvature of the mirror?

• A. 32 cm
• B. 64 cm
• C. 48 cm
• D. 80 cm

Answer 1

The correct option is B 64 cm

Given, u = – 40 cm
Magnification, $m=\frac{-v}{u}=-4$ (real and inverted image)
Therefore, v = –160 cm
By using the mirror formula, we get,
$\frac{1}{v}+\frac{1}{u}=\frac{1}{f}$
$\frac{1}{-160}+\frac{1}{-40}=\frac{1}{f}$
f = –32 cm
Since, f = R/2
R = 2 x –32 = –64 cm
Hence, the radius of curvature is 64 cm.