Electricity and Magnetism > DC Circuits DCS# 5F20.xx

TWO SOURCES OF EMF


APPARATUS
two DC power supplies 202-08-D
two 6 V light bulbs and sockets 202-19-E3
switch 101-09-D4


DESCRIPTION
First power supply is connected across the two bulbs in series, set to 8 volts or so, so that the bulbs light.  The second power supply is connected across a single bulb, and set to 4 V.  Show that closing the switch to the second power supply has no effect on the circuit.  This illustrates one of the Mazur questions.

NOTE

Connect second power supply only momentarily, in case the voltages are not identical.