Two waves of same frequency and same amplitude from two monochromatic sources are allowed to superpose at a certain point. If in one case the phase difference is 0 and in other case it is `pi//2` then the ratio of the intensities in the two cases will be

Options

A. `1:1`
B. `2:1`
C. `4:1`
D. `1:4`

Answer

B

Explanation

`(I _(res ) )_(A ) I+I+2sqrt(|) sqrt(|) cos 0 ^(@)`
`(I_(res ) )_(A) = 4I`
`(I_(res) )_(B ) =I +I + 2 sqrt(|)sqrt(|)cos 90 ^(@)`
`(I_(res ) )_(B) = 2I`
`(L_(Res ))_(A)/( (I_(res ))_(B))=(4I)/(2 I)=(2)/(1)`