1.

Fig. Shows two coherent sources S_(1) and S_(2), emitting wavelength lambda.The separation S_(1)S_(2) = 1.51. S_(1) is ahead in phase by (pi)/(2) relative to S_(2).The maxima occurs in a direction given by sin^(-1) of :

Answer»

`0`
`1/2` only
`1/6` only
`1/2 - 1/6 and -5/6`

Solution :`DELTA` is PHASE difference of waves between `S_(1)` and `S_(2)` at PT. P
`delta =((2PI)/(lambda) d sin THETA + pi/2)`

For maximaat P,
`delta = n pi, n = 0, pm1, pm2`...
`therefore (2pi)/(lambda).d sin theta + pi/2 = n pi`
`(2pi)/(lambda)(1.5 lambda sin theta) = (n - 1/2)pi`
`therefore 3 sin theta = (n - 1/2)`
`thereforesin theta = ((n -1/2))/(3)`
For n = 0"`sin theta = -1/6`
`n = pm 1"sin theta = 1/6, -1/2`
`n = pm2"sin theta = 1/2, -5/6`


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