Electric Lamps in Series and in Parallel


Two lightbulbs, a switch, and 4 wires rest on a table top

Concept Overview:

1. In series, the bulb with the smallest wattage burns the brightest.

2. In a series circuit, there is only one path for current to follow.  In a parallel circuit, there are multiple paths for current to follow.

Lecturer Procedure

Step(s) to Follow Expected Result

1. Turn switches in both sockets to the OFF position.

2. Wire lamps in series.

3. Connect series circuit to AC switch

4. Turn on small lamp.

Lamp will not turn on since there is a break in the circuit

1. Turn small lamp off.

2. Turn large lamp on.

Lamp still will not turn on since there is a break in the circuit.

1. Turn both lamps on.

2. (optional) Use a voltmeter to show how potential drop is distributed across the bulbs.

Small lamp lights brighter than large lamp.
1. Connect bulbs in parallel and repeat the above steps. If one bulb is turned off, the other is unaffected.  Additionally, their brightness will correspond to their wattage

The lecturer may choose to vary this demonstration by adding additional bulbs of similar or different wattage to fit the specific needs of their lesson.


There are no spoken words with this recording.

E&M: C - 002