1.

The interference patterns is obtained with two coherent light sources of intensity ratio n. I the interference pattern, the ratio (I_("max")-I_("min"))(I_("max")+I_("min")) will be......

Answer»

`(SQRT(n))/((n+1)^(2))`
`(2sqrt(n))/((n+1)^(2))`
`(sqrt(n))/(n+1^(2))`
`(2sqrt(n))/(n+1^(2))`

Solution :LET intensity of light be `I_(1) and I_(2)`
`:. (I_(1))/(I_(2))=n`
`(A_(1)^(2))/(A_(2)^(2))=n "" [ :. I PROP A^(2)]`
`:.(A_(1))/(A_(2))= sqrt(n)`
Taking COMPONENDO and dividendo
`(A_(1)+A_(2))/(A_(1)-A_(2))=(sqrt(n)+1)/(sqrt(n)-1)`
`:. ((A_(1)+A_(2))^(2))/((A_(1)-A_(2))^(2))=(n+2sqrt(n)+1)/(n-2sqrt(n)+1)`
`:. (I_("max"))/(I_("min"))=(n+2sqrt(n)+1)/(n-2sqrt(n)+1)`
Taking componendo and dividendo again
`(I_("max")-I_("min"))/(I_("max")-I_("min))=(n+2sqrt(n)+1-n+2sqrt(n)+1)/(n+2sqrt(n)+1+n-2sqrt(n)+1)`
`=(4sqrt(n))/(2(n+1))=(2sqrt(n))/(n+1)`


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