Make a Circuit

Circuits allow electricity to flow in a circular path from a positive to a negative lead. Simple circuits make a great tool for teaching basic electrical concepts, and for experimenting with electricity at home. Building a circuit is not hard as long as you have a power source, some wires, and a light bulb (or other electrical component). If you want to learn even more about circuits, you can attach a simple switch that allows you to turn the bulb on and off. While this isn’t necessary, it does demonstrate open and closed circuits nicely.

Steps

Using a Battery

  1. Screw a bulb into a bulb holder. A bulb holder is a device made to hold a light bulb. It also has two terminals. One is for a positive lead and the other is for a negative lead. This allows you to pass a current through the light bulb in the holder. Be sure to use a low powered light bulb (e.g. something in the range of 1-10 volts).[1]
  2. Remove about an inch of wire covering from each end of two copper wires. You should use two different colored copper wires. This will help you differentiate between the positive and negative lead. Use a knife or wire strippers to cut an inch of the wire insulation (the colored part) off of each end of both wires. This exposes the copper wire underneath.[2]
  3. Connect the positive lead. Generally, red wire is used to connect the positive end. One side of the red wire will connect to one side of the bulb holder. The other side of the red wire should touch the positive lead on the battery.[1]
  4. Connect the negative lead. Black wire is usually used to connect the negative end. Again, one end of the wire should touch the terminal on the bulb holder (not the same terminal as the positive wire). The other end of the wire can be left unattached until you are ready to light the bulb.[1]
  5. Light the bulb. Touch the unattached end of the negative (black) wire to the negative terminal on the battery. This completes the circuit and allows electricity to flow. The electricity is forced to flow through the light bulb, which causes the bulb to light up.

Using a Power Pack

  1. Set the power pack. The power pack should be on a flat, level surface. Plug the power pack into an outlet. This will provide a steady supply of power to your circuit. Plug the wire leads into the power pack.[2]
  2. Connect the light. Screw the light into a bulb holder. Then connect each lead from the power pack to one of the terminals on the bulb holder. Once both leads are connected, the light will light up.[1]
    • If the light does not light up, check that the leads are well connected and the power pack is plugged in and turned on.
  3. Adjust the voltage. You can turn a dial on your power pack to cause the voltage to fluctuate. Doing this can demonstrate how the brightness of the light changes as a result of higher or lower voltages. The light should get dimmer as the voltage goes down, and brighter as the voltage goes up.[2]

Adding a Switch

  1. Cut one wire lead. Remove power from the circuit before cutting any leads. It does not matter if you cut the positive or negative lead. You can use a pair of wire cutters to cut the lead anywhere in the circuit. The switch will provide control of the circuit no matter where it is located.[3]
    • It is dangerous to cut into a live wire (one with power on it). Always disconnect the circuit before cutting leads.
  2. Attach the lead wire from the battery to the switch. Once you have cut one of the lead wires, you can attach it to the switch. The switch will have two simple terminals. Attach the lead wire coming from the battery to one of these terminals.[3]
  3. Attach the lead wire from the switch to the bulb. The second piece of wire should be attached to the bulb holder terminal. Attach this piece of wire to the second terminal on the switch. This will again complete the circuit.[3]
  4. Toggle the switch. As you flip the switch on and off, it will open (break) and close (complete) the circuit. This will either prevent or allow electricity to flow. When the circuit is open, the light will be off. When the circuit is closed, the light will turn on.[3]

Video

Warnings

  • Do not use more than nine volts or a mild shock is possible.
  • The light bulb can become hot, do not touch it while it is on.

Things You'll Need

  • Light bulb
  • Light bulb holder
  • 2 wires of different colors (copper works best)
  • A 9 volt battery
  • A switch

Related Articles

Sources and Citations

  1. ↑ 1.0 1.1 1.2 1.3 https://www.homesciencetools.com/a/circuit-science-projects-for-elementary
  2. ↑ 2.0 2.1 2.2 http://www.energizer.com/science-center/make-a-simple-circuit
  3. ↑ 3.0 3.1 3.2 3.3 https://www.allaboutcircuits.com/textbook/experiments/chpt-2/circuit-with-a-switch/
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