Path difference and Coherence

Question 1

Coherence

Answer 1

• The two waves have the same frequency and wavelength and a fixed phase relationship

Question 2

Interference

Answer 2

• Happens when two waves are superposed
• To see clear interference the wave must be coherent

Question 3

Path difference

Answer 3

• Is the difference in length travelled to a point

Question 4

Path difference
(Inphase)

Answer 4

• If the path difference is a multiple of λ the waves will be in phase and you will see constructive interference
  Path difference = nλ

Question 5

Path difference
(Out of phase)

Answer 5

• If the path difference is a whole number plus a half λ the waves will be exactly out of phase
  Path difference is (n+1/2)λ