Question

In a biprism expeirment the slit is illuminated with light of wavelength 4800Å. The distance between the slit and eyepiece is 80 cm. the sources is then replaced by another source with a light of wavelenght 5400Å. The slit and biprims are not disturbed. The distance between the slit and eyepiece so that band widht increases by 8% as compared toe arlier band with is
A. `1.77 m`
B. `2.77 m`
C. `0.77 m`
D. `1.57 m`

Answer 1

Correct Answer - C
`beta_(1)=(D_(1))/(d)lamda_(1)=(0.8xx4.8xx10^(-7))/(d)m`
`beta_(2)=1.08xxbeta_(1)`
`=(1.08xx0.8xx4.8xx10^(-7))/(d)=(D_(2)xx5.4xx10^(-7))/(d)`
`:.D_(2)=(1.08xx4.8xx0.8)/(5.4)=(1.08xx8xx0.8)/(9)`
`=0.12xx6.4=0.768m`