1. Interference of Light

2. Refraction (a review)
Character of the wave in different (transparent) media
wave travels slower
Index of refraction n = c/v
frequency is constant (wavelength changes)
Law of Refraction (Snell’s Law) n1 sin q1 = n2 sin q2

3. Huygens Principle
Propagation of plane wave by Huygen’s principle

4. Snell’s Law
Refraction
Similar triangles

5. Young’s Double Slit

6. Young’s Double Slit 1801
Conditions for interference

7. Young’s Double Slit
Constructive interference phase difference to be an integral number of wavelengths

8. Destructive Interference Condition
Destructive interference (minima)

9. Young’s Double Slit
Intensity behavior

10. Young’s Double Slit
Intensity behavior algebraic approach

11. Intensity by Phasor Method

12. Young’s Double Slit
Intensity behavior averaged over one period

14. Interference upon Reflection
Thin Film
in air
coatings

15. Phase changes upon Reflection
Dense to less dense
n1 > n2
Less dense to more dense
n1 < n2

16. Thin Film in Air (Soap Film)
Assume
Near normal incidence
Conditions for reflected light interference
Condition for there to be
constructive interference

17. Michelson Interferometer