Circuit 2: Bulb + Switch

This circuit illustrates how a switch can function as a controller in a circuit. It gives you the ability to intentionally open and close a circuit. In this case it turns the light on or off. Other applications might be turning a fan, a motor, or a radio on or off.

This circuit looks like:

Follow the video below to build this circuit on your own workbench.

Understanding This Circuit

1. Using your hand, with the switch closed so the light is on, trace the path the electricity takes. Start at the battery and follow the path until you get back to the battery on the second lead.
2. Using the multimeter, with the battery leads disconnected so there is no power to your circuit:
   1. Remember or recheck the resistance of the bulb.
   2. Determine resistance of the switch. Where do you put the probes? Why? Based on what you found, do you think the switch adds to the load in a circuit?
   3. Determine resistance of a wire (use one of the unattached wires). Based on the reading you get, do you think the wire is considered a load or a conductor?

Feel like you've got this circuit mastered? Move to the next page and let's build another one.