Two coherent sources of intensity ratio `1:4` produce an interference pattern. The fringe visibility will be

Options

A. 1
B. 0.8
C. 0.4
D. 0.6

Answer

B

Explanation

` (I_(i))/(I_(2)) = (1)/(4) rArr I_(1) = K and I_(2) = 4k`
`therefore ` Fring `V = (I_(max) - I _(min))/(I_(max) + I_(min)) = (2 sqrt(I_(1)I_(2)))/(I_(1) + I_(2))`
` therefore` Fringe visibility
`V = ( 2 sqrt(I_(1)I_(2)))/((I_(1) + I_(2))) = (2sqrt(K xx 4K))/((K + 4K)) = 0.8`