A capacitor charges and discharges with a long time constant through a light whose brightness indicates the current.
Charge and discharge of a capacitor.
Above: Charging the capacitor. Download (right-click and “save link as”): Cap Charge.m4v (4 MB)
Below: Discharging the capacitor. Download (right-click and “save link as”): Cap Discharge.m4v (5 MB)
NCEA & Science Curriculum
Charge an electrolytic capacitor through a light bulb. As the capacitor charges the current falls off and the light bulb dims. Then disconnect the power supply and discharge the capacitor through the light bulb. As the capacitor discharges the current again falls off and the bulb dims.
Always make SURE that electrolytic capacitors are connected with the correct polarity. Never reverse bias an electrolytic capacitor as it may explode. No kidding.
Individual teachers are responsible for safety in their own classes. Even familiar demonstrations should be practised and safety-checked by individual teachers before they are used in a classroom.
Charge and Discharge a capacitor through an ammeter. Create a spark with a sudden discharge.
Would you like to contribute lesson suggestions? Contact us.
PIRA 5C30.30, PIRA 5F.30.10
This teaching resource was developed with support from