Physics Dept. Demonstration Manual

DEM63.1 - The 1 Farad "Supercap"


To show that current is induced in a secondary coil by rising and collapsing magnetic field in the primary, adjacent coil.

  • Custom network, c/w 1 Farad capacitor, lamp and
    double-throw switch for discharging or charging.
  • 6 volt lantern battery
  • small DC motor with propeller blade


Connect the fan/motor to the red/black terminals. With
the knife switch open, connect the 6 volt lantern battery
(red,positive). Move the switch to the right (charge).
The lamp and motor will be on, due to the charging
current through them. After about 45 seconds, the lamp
will be virtually out, but the motor will still operate for
about another minute. Charging of the supercap is now

Move the switch to the left (discharge). The stored
energy in the supercap will light the lamp and spin the
motor, for the samr time as for charging. Disconnect
the battery to show that the energy is coming from the