1. PHYS 221 Recitation Kevin Ralphs Week 11

2. Overview HW Questions Diffraction Interference

3. Diffraction What does it tell me? – How a wave behaves near objects – Only an appreciable affect when the length scale of the wave and the geometry are similar Visible light: 400nm – 700nm Sound waves: 17mm – 17m

4. Interference What does it tell me? – How waves mix together – Always occurs, but is appreciable only when the waves are coherent – Based on the principal of superposition Waves add together directly… intensities don’t if the light is coherent! The square root of intensities for coherent light will

5. Interference

7. Main Strategy For any kind of diffraction or interference problem, the game is always about counting up possible sources of interference and setting that equal to the interference condition you want

8. Topics Double Slit Interference Single Slit Diffraction Diffraction Gratings Optical Resolution and Rayleigh Criterion