In a double-slit experiment, two beams of coherent light traveling different paths arrive on a screen some distance away. What is the path difference between the two waves corresponding to the third bright band out from the central bright band?
Destructive interference occurs when path difference = ½-integer
multiple of the wavelength i.e. Minima in diffraction pattern given by,
= ! +
# λ = !1 +
# λ = 3λ/2
m
