Circuits Circuit Basics An 'open circuit' The simple circuit shown above is typical of what we may see in a flashlight.
Electrical current wants to flow from one side of the battery to the other.
If a light bulb is in the path that the electricity wants to take it will light up when the electrical current flows through it. When Switch 1 is open as shown. The light bulb does not light because the electrical path through the light bulb to the other side of the battery is broken or 'opened up'. If current cannot flow around the circuit it is said to be 'open'. It may be desirable to open a circuit, like ours, to turn off the light coming from a bulb.