electricity.jpg (5852 bytes)

POTENTIOMETER



EQUIPMENT
    redball.gif (326 bytes) Demonstration Potentiometer Device
    redball.gif (326 bytes) Small Power Supply
    redball.gif (326 bytes) Projection Galvanometer
 


NARRATIVE
            The Potentiometer is a device for measuring the EMF of a device without drawing a current from the rest of the EMF. The circuit board includes a good 1.5 Volt hobby cell, and a bad 1.5 Volt hobby cell and a shunt resistor for the projection galvanometer. The small power supply is connected to the circuit from behind the board to act as the 3 Volt working battery. The projection galvanometer may be damaged when the hobby cells are used, so use the shunt resistor until no meter deflection is detectable, and then remove it to get an accurate measurement. Put the galvanometer on the overhead projector.