light travelling in air is incident on a soap bubble. If the path difference through the soap bubble is 2.5λ:

a) constructive interference will occur
b) destructive interference will occur
c) partial interference will occur
d) none of the above

Would the answer be a?

1 answer

upon reflection on the inner surface, another 180deg shift occurs, so the path lenght is 3.0 wavelength, so it is constructive interference.