A parallel coherent beam of light falls on a Fresnel biprism of refractive index and…

PHYSICS · Single correct · AP · Physics 2: Algebra-based · Waves Sound and Physical Optics · Waves Sound and Physical Optics

Problem

A parallel coherent beam of light falls on a Fresnel biprism of refractive index

\mu

and refracting angle

\alpha

. The fringe width on a screen at distance

D

from the biprism, for wavelength

\lambda

, is: (a)

\frac{\lambda}{2(\mu-1)\alpha}

(b)

\frac{\lambda D}{2(\mu-1)\alpha}

(c)

\frac{D}{2(\mu-1)\alpha}

(d) None of these