Build a Simple Circuit
Connect a battery to a light bulb and discover how electrical circuits work. Then test which materials conduct electricity!
Adult supervision recommended for younger children.
This experiment uses low-voltage batteries which are safe. An adult should help with any cutting or stripping of wire.
Safety First!
- • Only use AA or 9V batteries — never plug into mains electricity.
- • Do not connect wire directly across both battery terminals without a bulb (this creates a short circuit and heats up the wire).
- • If wire gets warm, disconnect immediately.
- • Do not put batteries in your mouth or near water.
You Will Need
Step-by-Step Instructions
Understand Your Battery
Look at your battery. It has two ends: a positive (+) end (usually with a bump) and a negative (-) end (usually flat). Electricity flows from one end, through your circuit, and back to the other end.
Build Your Circuit
Cut or tear two strips of wire (or aluminium foil). Tape one strip to the positive (+) end of the battery. Tape the other strip to the negative (-) end. Now touch the free ends of each strip to the two legs (or contacts) of your LED or bulb.
Light It Up!
If your connections are good, the LED or bulb should light up! If it does not, try swapping which wire connects to which leg of the LED (LEDs only work one way around). Make sure all connections are tight.
Break the Circuit
Now disconnect one wire from the battery. What happens? The light goes off! For electricity to flow, the circuit must be a complete loop — no gaps allowed.
Test Conductors and Insulators
Disconnect one wire from the bulb, leaving a gap in your circuit. Now place different objects across the gap to see if they complete the circuit and make the light turn on. Try a paperclip, rubber band, coin, wooden pencil, plastic ruler, aluminium foil, and eraser.
Record Your Results
Make a table with columns: Object, Material, Light On?, Conductor or Insulator?. Record what you find for each object.
Extension: Draw Your Circuit Diagram
Scientists use special symbols to draw circuits. Draw your circuit using a rectangle for the battery, a circle with an X for the bulb, and straight lines for the wires. Can you add a switch (a gap in the line that can open and close)?
Sample Results Table
| Object | Material | Light On? | Type |
|---|---|---|---|
| Paperclip | Metal | Yes | Conductor |
| Rubber band | Rubber | No | Insulator |
| Coin | Metal | Yes | Conductor |
| Pencil (wood) | Wood | No | Insulator |
| Aluminium foil | Metal | Yes | Conductor |
| Plastic ruler | Plastic | No | Insulator |
What Happened?
When you connected the battery to the LED with wires, you created a complete circuit — a loop that electricity can flow around. The battery pushes electrical energy through the wire, through the LED (making it light up), and back to the battery.
When you broke the circuit by disconnecting a wire, the electricity could not flow because there was a gap. No flow means no light!
When you tested different materials, you discovered that metals (like paperclips, coins, and foil) let electricity flow through them — they are conductors. Materials like rubber, plastic, and wood block electricity — they are insulators.
The Science Behind It
An electrical circuit is a complete path that electricity can flow around. It needs: a power source (battery), wires to carry the electricity, and a load (something that uses the electricity, like a light bulb).
Electricity is the flow of tiny particles called electrons. The battery pushes electrons through the wire. They flow around the circuit and back to the battery — but only if the path is complete.
Conductors are materials that let electrons flow through them easily. Most metals are excellent conductors because their electrons can move freely. Insulators are materials that block the flow of electrons — their electrons are held tightly in place.
This is why electrical wires are made of metal (conductor) but wrapped in plastic (insulator) — the metal carries the electricity while the plastic protects you from getting a shock!
Think About It
Why are electrical wires made of metal on the inside but covered in plastic on the outside?
What happens if you use a longer piece of wire? Does the bulb get dimmer? Why might that be?
A light switch in your house breaks the circuit to turn a light off and completes it to turn it on. Can you design a simple switch for your circuit?
What would happen if you added a second battery to your circuit? What about a second bulb?
Knowledge Check
Test what you have learned! Select the correct answer for each question.
Question 1
What three things does a simple circuit need?
Question 2
A material that lets electricity flow through it is called a...
Question 3
Which of these is an insulator?
Question 4
Why does a light bulb go off when you disconnect a wire from the battery?
Question 5
Why are most electrical wires made of copper (metal)?
Key Concepts Summary
- ● An electrical circuit is a complete loop that electricity flows around.
- ● A circuit needs a power source (battery), wires, and a load (like a bulb).
- ● Conductors (like metals) let electricity flow through. Insulators (like rubber and plastic) block it.
- ● If the circuit is broken (has a gap), electricity cannot flow and the light goes off.
- ● A switch is a device that opens and closes a gap in a circuit to control the flow of electricity.