Q. One face of a rectangular glass plate $6\ cm$ thick is silvered. An object held 8 $cm$ in front of the first face, forms an image $12\ cm$ behind the silvered face. The refractive index of the glass is
A) $0.4$
B) $0.8$
C) $1.2$
D) $1.6$
Explanation
(c) Let $x$ be the apparent position of the silvered surface
According to property of plane mirror
$x + 8 = 12 + 6 - x \Rightarrow x = 5\ cm$
Also $\mu = \frac{t}{x} \Rightarrow \mu = \frac{6}{5} = 1.2$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.