- Load - A device that does work or performs a job (i.e., the light bulb in our circuit).
- Electrical current - The flow of electrons from an area of high concentration (“a lot”) to an area of lower concentration. *Note: the negative side of the battery has a high concentration of electrons.
- Electron - A negatively charged particle that orbits the nucleus of an atom.
- Generator - A device that converts mechanical or chemical energy into electricity. Wind, water or an engine can power a generator.
- Electrical circuit - An electrical path that is closed (all parts connected), allowing the electricity to return to the original source (the battery).
- Parallel Circuit - A circuit in which the components are connected like a ladder. This circuit splits the voltage equally to all of the components.
Creating a Simple Circuit
- Place a “D” cell battery in a battery holder. The battery holder will allow you to attach wires with alligator clips to the positive and negative ends of the battery.
- Now, screw a small light bulb (mini lamp) into a lamp holder. Like the battery holder, the lamp holder will allow you to attach alligator clips to the light bulb (your load).
- To complete the circuit, you will need two wires with alligator clips. Use one wire to connect the negative side of the battery to the lamp holder. It does not matter which side of the lamp holder the wire is attached. Connect the positive side of the battery to the lamp holder using the second wire. This wire will attach to the opposite side of the lamp holder. The light bulb should be lit.
Remember, the voltage of the battery and light bulb should be similar. If the battery voltage is too much larger than the voltage capacity of your bulb, the bulb will burn out. A “D” cell battery provides 1.5V.
Adding a Knife Switch to a Simple Circuit
We will modify our simple circuit described above to complete this task.
- Disconnect the alligator clip that is attached to the negative side of the battery and re-connect it to one side of the knife switch. Make sure the knife switch is in the upright position.
- Take a separate wire and connect the negative side of the battery to the knife switch. Notice that the light is off.
- Lower the arm on the knife switch to connect the circuit and light the bulb.
The knife switch allows you to discuss breaking the circuit and stopping the flow of electrons.
Heath Scientific provides a kit called “Making Circuits Simple” that includes all of the components described in this article. It’s an easy, all-in-one kit to demonstrate circuits to your students.