Question

If prism angle `alpha=1^@`, `mu=1.54`, distance between screen and prism `(b)=0.7m`, distance between prism and source `a=0.3m`, `lambda=180pi nm` then in Fresnel biprism find the value of `beta` (fringe width).
A. (a) `10^-4m`
B. (b) `10^-3mm`
C. (c) `pixx10^-4m`
D. (d) `pixx10^-3m`

Answer 1

Correct Answer - A
By using
`beta=((a+b)lambda)/(2a(mu-1)a)=((0.3+0.7)xx180pixx10^-9)/(2xx0.3(1.54-1)xx(1xxpi/180))`
`=10^-4m`