Resistance (D+55)

  D+55+0 Resistance boards: Series, parallel, Wheatstone bridge.
  D+55+2 Watt's law: Variable resistor, glow coil, volt and amp meter.
  D+55+4 High current melts the fuse wire.
  D+55+5 Conductivity of solution with free ions
  D+55+6 Resistance thermometer: Iron coil in liquid Nitrogen and flame varies current.
  D+55+8 Effect of temperature on current in carbon or tungsten filaments.
  D+55+10 Large tungsten filament lamp; as it heats, current drops.
  D+55+12 Oscillator with resistor, capacitor and neon lamp.
  D+55+13 Same as D+55+12 using speaker for audio tone generation.
  D+55+14 Same as D+55+12 using oscilloscope to display waveform.
  D+55+16 Film: "Elementary electricity", sound; 8 min.
  D+55+18 Resistor analog: Marbles cascading down pin board.