A Young’s double-slit experiment is performed with monochromatic light of wavelength 520nm. At a point P on the screen the waves from the two slits travel distances that differ by 1.56μm.
(i) Calculate the phase difference between the two waves at P in (a) radians and (b) degrees.
(ii) State whether point P will appear bright or dark in the interference pattern. Give a brief justification.