Q. A glass slab of thickness $3\ cm$ and refractive index 3/2 of placed on ink mark on a piece of paper. For a person looking at the mark at a distance $5.0\ cm$ above it, the distance of the mark will appear to be
A) $3.0\ cm$
B) $4.0\ cm$
C) $4.5\ cm$
D) $5.0\ cm$
Explanation
(b) The apparent depth of ink mark
$= \frac{real\ depth}{\mu} = \frac{3}{3/2} = 2\ cm$
Thus person views mark at a distance $= 2 + 2 = 4\ cm$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.