- Do you have a flashlight?
- Have you ever looked inside it?
A flashlight won't light up unless there are batteries inside.
When you switch it on, the batteries make an electric current flow.
This current flows through the bulb and makes it light up.
When you switch on a flashlight, the batteries inside create an electric current by making electrons move. The electric current flows out of one end of the battery, through the bulb, and then back into the battery.
As long as the current can move freely around this pathway, the bulb will light up.
We call this kind of pathway an electric circuit.While the flashlight is switched on, the current continues to flow around and around the circuit. Turning the switch off makes a break in the circuit. Now the current can't flow, and the light goes out.
Electric Circuit experimentYou will need:
- two pieces of plastic-coated wire, about 8 inches (20 cm) long, with bare ends
- a screwdriver
- masking tape
- a 1.5-volt("D") battery
- a 1.5 volt battery bulb holder
Which bulb will light up?
An electric current won't flow if it can't make a complete trip around a circuit.
You can test this for yourself.
Set up the simple circuits shown below.
Can you guess which one will make the bulb light up?
1. Tape one end of a piece of wire to the top battery terminal.
Connect the other end of this wire to one side of the bulb holder.
Does the bulb light up?
2. Now connect the other circuits shown here.
Which one is a complete circuit?
Positive and negative terminalsA battery has two connections where the electric current flows in or out.
These connections are called terminals.
Sometimes, as in most flashlight batteries, the terminals are on either end of the battery. Other batteries have both terminals on one end.
- One terminal is marked + (plus).
- The other terminal is marked — (minus).
The electric current flows out of the terminal marked plus, the positive terminal.
The current flows into the terminal marked minus, the negative terminal.