# Two rays of light travel as shown.The refractive index of material is 3/2 and that of the surrounding is 4/3. What is the path difference between the two.

$(a)\;\frac{t}{4} \\ (b)\;\frac{t}{8} \\ (c)\;\frac{2t}{3} \\ (d)\;\frac{3t}{2}$

Path difference
$\Delta =\bigg(\large\frac{\mu_2}{\mu_1}$$-1\bigg) t$
$\Delta x = \bigg(\large\frac{\Large\frac{3}{2}}{\Large\frac{4}{3}}-1 \bigg) t$
$\qquad= \large\frac{t}{8}$
Hence b is the correct answer.
answered Jan 22, 2014 by