A printed page is kept pressed by a glass cube-shaped paper-weight of edge 3.0 cm. The refractive index of the glass is \( \mu = 1.5 \). By what amount will the printed letters appear to be shifted when viewed from the top ?
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → 1.0 cm
For an object under a slab of thickness \( t \) and refractive index \( \mu \), viewed normally from the top, the apparent depth is \( t/\mu \). The letters appear raised by the difference.
\( \displaystyle \text{shift} = t - \frac{t}{\mu} = t\left(1 - \frac{1}{\mu}\right) \)
\( \displaystyle \text{shift} = 3.0\left(1 - \frac{1}{1.5}\right) = 3.0\times\frac{1}{3} = 1.0\,\mathrm{cm} \)
Note: NTA picked this question from an NCERT (2026-27) exercise and changed the figures. Do not ignore NCERT while practising numericals.
NCERT (2026-27):
Exercises – …
