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# Phase difference/ path difference

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1. So I'm doing homework on superposition and polarisation and there's a question on phase difference/ path difference that i have no idea how to answer. These are the questions:

b) path differences give rise to phase differences. By how much do the following change the phase difference?
(i) 1 wavelength
(ii) wavelength/2
(iii) 3 wavelength/4

c) What path differences would give the following phase differences?

(i) 90 degrees
(ii) 120 degrees
(iii)540 degrees

Any help would be great!!
2. it's a linear relationship

Dφ(in degrees)=360(Dl/λ)

so... if difference in path (Dl) = 0λ
then difference in phase (Dφ) = 0 degrees

if difference in path = 100λ
then difference in phase = 36000 degrees

etc.

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