When waves from two coherent source of amplitudes a  and b superimpose , the amplitude
Channel: Doubtnut
Date: 2020-05-09

When waves from two coherent source of amplitudes a  and b superimpose , the amplitude R of the resultant wave is given by R = `sqrt(a^(2)+b^(2)+2ab cos phi). `  where `phi` is the constant phase angle between the two waves. The resultant intensity I is directly proportional  to the square of the amplitude of the resultant wave i.e `I prop R^(2)` i.e,  `I prop (a^(2) +b^(2) +2ab  cos phi )` For constructive interference ,  `phi = 2n pi " ""and"" " I _("max") = (a+b)^(2)`   For destructive interference ,  `phi = (2n-1) pi "and"  I_("min") = (a-b)^(2)`  If `I_(1) I_(2)` are intensities from two slits of width `w_(1) "and" w_(2) ` then   `I_(1)/I_(2)=w_(1)/w_(2)=a^(2)/b^(2)`   Light waves from two coherent sources of intensity ratio 81 : 1 produce interference. With the help of the passage choose the  most appropriate  alternative for each of the following questions   The ratio of slit widths of the two sources is