Newton’
s Rings
Interference appears at the waves adding, reflected from the two sides of air gap. «Rays» 1 and 2 are the directions of waves propagations; h is the thickness of the air gap.
Newton’
s Rings
2 
For dark rings
cos ' 1
Newton’s Rings 3
rm 
Rm
This is a special case of strips of equal thickness, which are created in the air gap between the spherical lens and the plane. It is better to observe them in the reflected light. Herewith in the centre of the picture because of the phase shift (for the air gap from the second boundary the phase shift = π) at the reflection there is the dark spot, in the centre m=0. Pictures of the rings in the reflected and last light are the additional, at any point of the gap the sum of their 
intensities is constant and equals to the intensity of the incident plane wave.
The Michelson Interferometer
Quick Quiz 1 
In a two-slit interference pattern projected on a screen, the fringes are equally spaced on the screen
(a)everywhere
(b)only for large angles
(c)only for small angles.
Quick Quiz 2 
Which of the following will cause the fringes in a two-slit interference pattern to move farther apart?
(a)decreasing the wavelength of the light
(b)decreasing the screen distance L
(c)decreasing the slit spacing d
(d)Immersing the entire apparatus in water.
Quick Quiz 3 
In a two-slit interference pattern projected on a screen, the fringes are equally spaced on the screen
(a)everywhere
(b)only for large angles
(c)only for small angles.
Quick Quiz 4
At dark areas in an interference pattern, the light waves have canceled. Thus, there is zero intensity at these regions and, therefore, no energy is arriving. Consequently, when light waves interfere and form an interference pattern, (a) energy conservation is violated because energy disappears in the dark areas (b) energy transferred by the light is transformed to another type of energy in the dark areas (c) the total energy leaving the slits is distributed among light and dark areas and energy is conserved.
Quick Quiz 5 
One microscope slide is placed on top of another with their left edges in contact and a human hair under the right edge of the upper slide. As a result, a wedge of air exists between the slides. An interference pattern results when monochromatic light is incident on the wedge. At the left edges of the slides, there is (a) a dark fringe (b) a bright fringe (c) impossible to determine.