1. Interference

2. Interference l2- l1 = m λ (Constructive)
l2- l1 = (m+1/2) λ (Destructive)
m = 0,1,2,3,4,………

3. Thin film interference
2t = (m+1/2) λfilm Constructive
2t = m λfilm Constructive
2t = (m+1/2) λfilm Destructive
λfilm = nvac /nfilm

4. Phase Change
If light is reflected from a surface where n1 > n2 there is a ½ λ phase shift.
Zero or One phase shift
2t = m λfilm Constructive
2t = (m+1/2) λfilm Destructive
One phase shift
2t = (m+1/2) λfilm Constructive
2t = m λfilm Destructive

5. Light of wavelength 600nm impinges upon a soap film (n = 1
Light of wavelength 600nm impinges upon a soap film (n = 1.4) on top of glass (n = 1.5) . What is the smallest thickness of film that will produce constructive interference? (Assume the index of refraction of air is n= 1.0)

6. Light of wavelength 600nm impinges upon a soap film (n = 1
Light of wavelength 600nm impinges upon a soap film (n = 1.4) on top of plastic (n = 1.3) . What is the smallest thickness of film that will produce constructive interference? (Assume the index of refraction of air is n= 1.0)

7. Double slit Sin θ = m λ / d Constructive (bright)
Sin θ = (m + ½) λ / d Destructive (dark)

8. A double slit experiment is setup using light of wavelength, 600nm with a slit spacing of 2x10-5m. If the screen is located 5m from the slits how far from the pattern middle is the first bright, dark spot located?

9. Single slit/Barrier
Sin θ = m λ / w Dest. (dark)
m = 1,2,3,4,………

10. Diffraction grating Sin θ = m λ / d Const. (bright)
d = dist. between slits
d = 1/# of slits per m.

11. Missing bright spots in the double slit pattern
Sin θ = m λ / d Constructive (bright)
Single slit
Sin θ = m λ / w Destructive (dark)