PURPOSE: To show the quick release of the energy stored in a large capacitor.
DESCRIPTION: A large aluminum electrolytic capacitor is charged slowly using a power supply. A knife switched is opened to disconnect the capacitor from the power supply. The power supply is turned off. A nail at the end of a rod is shorted across the terminals of the capacitor. Different voltages may be used to show that the energy goes as the square of the voltage.
A safety shield protects the students, and safety glasses, ear protectors and gloves are provided for the faculty.
The ammeter can be used to show the charging current.
EQUIPMENT: Capacitor, knife switch are stored in the electricity and magnetism cabinets. The power supply is stored in the general use equipment cabinets. The safety shield is stored betwen the solid mechanics cabinets.
SETUP TIME: One half hour. It is strongly advised that the faculty
practice the demo the day before the class.