Capacitance

  • EM2.1 Parallel Plate Capacitor with Electroscope

    The circuit is set up as follows: the bottom of the Van de Graaf is attached to one end of the capacitor (PASCO, variable type); the other end of the capacitor is attached to to a switch which connects the capacitor either to the Van de Graaf generator or to a gold leaf electroscope. When the switch is connected to the generator, the capacitor builds up a potential difference. Turning off the generator and throwing the switch to the electroscope will discharge the capacitor, and the electroscope's leaves will repel each other. This shows that capacitors store charge. Variations of this include varying the distance between the plates of the capacitor and inserting a dielectric (same shelf) into the capacitor.

  • EM2.2 Relaxation Oscillator

    These are neon lights in series with capacitors. When the capacitors charge up, they dissipate their charge and cause the lamp to flash.

  • EM2.3 Wimshurst Induction Machine

    The classical Wimshurst machine separates charge. The hand crank spins two disks in opposite direction and charges two beakers, each with a unique charge. In essence, this creates a large capacitor. The capacitance of the machine can be controlled by two nobs in the front of the machine. When the knobs touch, the capacitance is high.