Electric Tennis Balls



Demonstrate the basic concepts of DC electricity using tennis balls.


A dozen tennis balls or similar balls


There are several technical terms that are useful, even vital, to understanding direct current electricity. Be sure to explain power, voltage, current, and resistance. Using a simple, mechanical analogy with tennis balls these terms can all be demonstrated and their relationships to one another explored. This activity is a good problem-solving/creative thinking activity – be sure to give the students plenty of time to come up with ideas.


Select a student to play the battery and another to be the light bulb. Place the light and battery on opposite sides of the room. Give the tennis balls to the battery. Explain that the idea is to give energy (tennis balls) to the bulb from the battery so that it can light up – but in order for this to happen we need a circuit. Ask students how to get tennis balls from the battery, to the light, and back to the battery.

Select pairs of students to stand at intervals between the battery and light. Half of the students in the circuit will transfer energy to the light, the other half will transfer energy back to the battery. The battery starts tossing balls in one direction down the line. Once they reach the light the balls are returned down the line. Try to keep the electricity flowing constantly.

Ask students how we can increase the power (P) that the bulb is receiving, and hence make the light brighter. One way is to throw the balls harder, simulating an increase in voltage (V). Similarly, the current (I) can be increased by throwing the balls at a faster rate. Remember, P = I x V.


Other components can also be added. For instance a switch might be represented by two people standing next to each other who can only pass the balls, not throw them, to each other and only when they are holding hands (closed) not when they are separated (open).