Question

2f and 2g please

2) A wave of wavelength 2 travels along a straight line between two points in space separated by distance L. a) Find the phase difference in the wave at these two points. _radians

Answer 1

f) Phase difference between two beam depends on the optical path difference between the two beams. Optical path is the product of distance L travelled by light in the material of refractive index n i.e optical path = nL.

Thus the phase difference between two beams depends on L1, L2 L3 as they are the thickness of the material and also in n1 , n2 and n3 as they are the refractive index of the material. The product of these two variables (L and n) will give the optical path length. The difference between the optical path length will give the optical path difference which inturn will give the phase difference.

g) The wavelength in vaccuum $\lambda_{v}$ dont matter because any change in wavelength due to change in medium (vaccuum to medium with refractive index n)is taken care by refractive index n. That implies,

$\lambda_{n}= \frac{\lambda_{v}}{n}$