EL.1(1) – Lamp Board
This lamp board demonstrates series and parallel circuits. Two sizes are available. It can demonstrate Kirchhoff’s circuit laws by measurements of voltage and current throughout the circuit. An interesting demonstration can be done using 25 watt and 200 watt light bulbs: when connected in series, the 25 watt bulb is brighter!! This lamp board does not obey Ohm’s Law, since the resistance of the filaments depends on temperature, and then on voltage (or current).
EL.1(2) – Circuit Puzzle
This is a circuit that looks very much like the canonical series circuit, but the switches and lights don’t do what is expected.
What components can be added to this circuit to give the observed behavior? One could think about the effects of common components such as resistors, inductors, capacitors, diodes, transistors, etc. It doesn’t involve magnets or radio frequency transmitters.
Solution: Diodes provide coding and decoding by phase of the AC current. A diode is put in parallel with the each switch and light.
Click here to see a video of this demo.