- #1
phalanx123
- 30
- 0
1. Light of wavelength L = 500nm, produced by an extended source, is incident
at an angle of 30o from the normal upon a dielectric film of refractive index n = 2
supported on a solid planar substrate. Reflectivity minima are observed to have an
angular separation of 0.05 radians. What is the thickness of the film?
I got a little confused because I thought that if the film have same thickness and horizontal and the incident light is at a constant angle than there wouldn't be any inteference fringes. They would either all be constructive, destructive or somewhere in between because the condition (phase difference/path difference) for each light ray is the same. Or have I misunderstood the geometry of the question? Is it that the film is laying horizontal and the light all incident at the same angle of 30o and interference fringes were created with angular separation of 0.05 rad between successive minima? I am so stuck on this question could somebody help me please
at an angle of 30o from the normal upon a dielectric film of refractive index n = 2
supported on a solid planar substrate. Reflectivity minima are observed to have an
angular separation of 0.05 radians. What is the thickness of the film?
I got a little confused because I thought that if the film have same thickness and horizontal and the incident light is at a constant angle than there wouldn't be any inteference fringes. They would either all be constructive, destructive or somewhere in between because the condition (phase difference/path difference) for each light ray is the same. Or have I misunderstood the geometry of the question? Is it that the film is laying horizontal and the light all incident at the same angle of 30o and interference fringes were created with angular separation of 0.05 rad between successive minima? I am so stuck on this question could somebody help me please