A printed page is kept pressed by a glass cube ($μ=1.5$) of 5 cm edge. By what amount will the printed letters appear to be shifted when viewed from the top?

1.7 cm

The correct answer is Option (3) → 1.7 cm

Given:

Refractive index of glass: $\mu = 1.5$

Edge of cube (thickness): $t = 5\ \text{cm}$

Apparent shift when viewed from top: $\Delta = t \left(1 - \frac{1}{\mu}\right)$

Substitute values:

$\Delta = 5 \left(1 - \frac{1}{1.5}\right) = 5 \left(1 - 0.6667\right) = 5 \cdot 0.3333 \approx 1.667\ \text{cm}$

∴ Printed letters appear shifted by ≈ 1.67 cm