Question

The coherent point sources `S_(1)` and `S_(2)` vibrating in same phase emit light of wavelength `lambda`. The separation between the sources is `2lambda`. Consider a line passingh through `S_(2)` and perpendicular to the line `S_(1)S_(2)`. What is the smallest distance from `S_(2)` where a minimum of intensity occurs due to interference of waves from the two sources?
A. `(7 lamda ) /(12) `
B. `(15 lamda)/( 4)`
C. `(lamda )/(2) `
D. `(3lamda) /(4) `

Answer 1

Correct Answer - A

` S_(1) P-S_(2) P=Delta x`
`sqrt((2h)^(2)+x^(2))-x=(3lamda)/(2)`
`4 lamda ^(2) f x^(2) -((3lamda )/(2)+x)^(2)`
`x=(7) /( 12 ) lamda `