Topics covered on Exam 1

Chapter 16 (except sections 4 and 6)

  1. Waves: general definition, wave speed, definition of absorption and dispersion (which we'll assume are negligible)
  2. Longitudinal and transverse; localized pulses and periodic (effectively infinite) waves
  3. y=g(x-vt) for wave moving towards positive x; g(x+vt) for wave moving towards negative x
  4. speed of wave on rope
  5. motion of pieces of medium, transverse speed
  6. Terminology for all periodic (repeating) waves: period, frequency, wavelength
  7. Periodic waves; v=fλ
  8. superposition of waves; sinusoids can build anything else
  9. Terms for sinusoidal waves: amplitude, phase, angular frequency, phase constant, wave number
  10. Power transmission by rope wave
  11. All waves: Power proportional to wave speed and to amplitude squared

Chapter 17

  1. Sound: longitudinal / compression-expansion / pressure / density wave
  2. Terms: Wavefronts, rays
  3. Phase difference between displacement and pressure
  4. Speed in air about 340m/s and depends on temperature, faster in solids and liquids
  5. Intensity and its relation to the Area over which wave spreads: Often intensity drops off as 1/r2
  6. Intensity proportional to Amplitude squared
  7. "Sound level," with the unit decibel, is an alternate way to specify loudness of sound.
  8. Doppler effect: moving source, moving detector (with respect to medium)
  9. Shock wave when source moves faster than sound speed. Formula for shock cone angle.
  10. Beats

1D Interference (Ch 16)

  1. Interference (= superposition with same frequency and wavelength):
  2. Co-moving Interference (amplitude equation): phase difference = phase constant difference
  3. All cases with sources that are in phase: Phase difference at a position is determined by [the difference in the distances of the sources from that position].
  4. Counter-propagating waves make standing waves if constituents have same amplitude

Reflection and Transmission (both Ch 17 and 35)

  1. Reflection at end of medium, reflection and transmission at media junction
  2. Reflected wave is inverted at fixed end or if 2nd medium has lower wave speed
  3. Reflected wave is upright at free end or if 2nd medium has higher wave speed
  4. Transmission: always up-right.
  5. Reflection reverses pulses left-to right, transmission doesn't
  6. Transmission into faster medium stretches wave shape; into slower medium compresses wave shape

Standing Waves (both Ch 16 and 17)

  1. On string: fixed ends limit vibrations to modes with specific wavelengths and frequencies
  2. Modes, harmonic number, nodes, antinodes, loops
  3. In air in tube: closed tube end makes fixed displacement, free pressure.  Open tube end is vice versa
  4. Standing waves with both ends free or both ends fixed: all harmonics
  5. Standing waves with one free and one fixed end: only odd harmonics

Chapter 35, sections 1, 2 and 4 (some 2-source interference in Ch 17)

  1. Two source interference: phase difference at a point depends on path length difference, conditions for constructive/destructive
  2. Two slit interference: just two source interference, with the approximation L1-L2=d sin θ
  3. For narrow patterns on a screen, additional approximation leads to the constructive interference requirement mλ=dy/D
  4. Speed of light in vacuum and through other materials; index of refraction; effect on wavelength (frequency unaffected)
  5. Phase differences due to passing through different media
  6. Thin film interference