- #1
Philip Wood
Gold Member
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Please consider this set up… A point source, P1, (with a finite coherence time) lies on the perpendicular bisector of the line joining two slits, S1 and S2. Therefore the slits are (secondary) in-phase sources of waves from P1,
A similar point source, P2, sending out waves of the same frequency and amplitude as P1, lies near P1 but a little way off the perpendicular bisector, such that S1 and S2 act as (secondary) antiphase-sources of waves from P2,
On the other side of the slits, no interference pattern will be formed, because wherever there is constructive interference due to waves from P1, there is destructive interference due to waves from P2, and vice versa.
My questions are: (1) Are S1 and S2 incoherent (secondary) sources? (2) Can the lack of an interference pattern in this case also be explained in term of coherence or lack of it?
Many thanks
A similar point source, P2, sending out waves of the same frequency and amplitude as P1, lies near P1 but a little way off the perpendicular bisector, such that S1 and S2 act as (secondary) antiphase-sources of waves from P2,
On the other side of the slits, no interference pattern will be formed, because wherever there is constructive interference due to waves from P1, there is destructive interference due to waves from P2, and vice versa.
My questions are: (1) Are S1 and S2 incoherent (secondary) sources? (2) Can the lack of an interference pattern in this case also be explained in term of coherence or lack of it?
Many thanks