If the ratio of the intensity of two coherent sources is 4 then the visibility `[(I_(max)-I_(min))//(I_(max)+I_(min))]` of the fringes is

Options

A. 4
B. `4/5`
C. `3/5`
D. 9

Answer

B

Explanation

`(I_(max))/(I_("min"))=((sqrt(I_(1))+sqrt(I_(2)))/(sqrt(I_(1))-sqrt(I_(2))))^(2)=((sqrt(4)+sqrt(1))/(sqrt(4)-sqrt(1)))^(2)=9`
Visibility `=(I_(max)+I_("Min"))/(I_(max)-I_("min")) =(((I_(max))/(I_("min"))-1))/(((I_(max))/(I_("min"))+1))=(9-1)/(9+1)=4/5=1`