In the Young's double slit experiment, the ratio of intensities of bright and dark fringes is 9. this means that

Options

A. the intensities of individual sources are 5 and 4 units respectively
B. the intensities of individual sources are 4 and 1 units respectively
C. the ratio of their amplitudes is 3
D. the ratio of their amplitudes is `3/2`

Answer

B

Explanation

`(I_(max))/(I_("min"))=((A_(1)+A_(2))^(2))/((A_(1)+A_(2))^(2))=9`
`therefore (A_(1)+A_(2))/(A_(1)-A_(2))=3" "therefore A_(1)+A_(2)=3A_(1)-3A_(2)`
`therefore 4A_(2)=2A_(1)" "therefore (A_(1))/(A_(2))=(2)/(1)`
`therefore (I_(1))/(I_(2))=((2)/(1))^(2)=(4)/(1)`
If `I_(2)=1,I_(1)=4`