Among the two interfering monochromatic sources A and B, A is ahead of B in phase by `66^@`. If the observation be taken from point P, such that `PB-PA=lambda//4`. Then the phase difference between the waves from A and B reaching P is

Options

A. (a) `156^@`
B. (b) `140^@`
C. (c) `136^@`
D. (d) `126^@`

Answer

A

Explanation

Total phase difference
=Initial phase difference+Phase difference due to path
`=66^@+(360^@)/(lambda)xxDeltax=60^@+(360^@)/(lambda)xxlambda/4`
`=66^@+90^@=156^@`