A mica strip and a polystyrene strip are fitted over the two slits of a double-slit…

PHYSICS · Single correct · CBSE · Physics · Wave Optics · Wave Optics

Problem

A mica strip and a polystyrene strip are fitted over the two slits of a double-slit apparatus. Their thicknesses are

0.50\,\mathrm{mm}

, and the slit separation is

0.12\,\mathrm{cm}

. The refractive indices of mica and polystyrene are

1.58

and

1.55

, respectively, for light of wavelength

590\,\mathrm{nm}

. Interference is observed on a screen

1\,\mathrm{m}

away. What is the fringe width? (a)

2.45\times10^{-4}\,\mathrm{m}

(b)

4.9\times10^{-4}\,\mathrm{m}

(c)

9.8\times10^{-4}\,\mathrm{m}

(d)

10^{-3}\,\mathrm{m}