Engineering
Simple Circuit Light
Make a tiny light turn on by building a complete path for electricity to travel through.
Medium · 1-2 hours
Introduction
Flipping on a light feels ordinary, but inside that tiny click is a big science idea called electricity.
This project is awesome because you will build your own working circuit and watch a real bulb light up from your design.
The Why
Electricity needs a complete loop, called a circuit, to move from one end of the battery to the other. When the path is closed, energy can travel through the wires and power the LED light.
Step-by-Step Instructions
- 1
Look at your battery, wires, and LED and find the two ends where electricity will enter and leave.
- 2
Connect one wire from the positive side of the battery to the long leg of the LED.
- 3
Connect a second wire from the short leg of the LED back to the negative side of the battery.
- 4
Tape the connections gently so the wires stay in place.
- 5
If the LED does not light, flip the LED around because LEDs only work in one direction.
- 6
Add a simple switch in one part of the circuit so you can open and close the path.
- 7
Test the switch and watch your circuit turn the light on and off.
What each part does
- Battery
- The power source. Electricity flows from the positive terminal (+) through the circuit and back into the negative terminal (−). A 9V battery or a small AA battery pack both work.
- LED
- Light-emitting diode. It only works in one direction — the long leg connects to positive, the short leg to negative. Flip it around if it does not light up.
- Wires
- The pathway electricity travels through. Insulated wire keeps the current going in one direction and prevents short circuits.
- Switch
- Opens or closes the circuit. When the switch is open, electricity cannot flow and the light goes out. When it is closed, the path is complete and the light turns on.
Troubleshooting
| Problem | Fix |
|---|---|
| LED does not light | Flip the LED around — polarity is wrong. |
| LED lights but is very dim | Check all wire connections. A loose contact reduces current. |
| Nothing happens at all | Check the battery has charge and both wires are connected firmly. |
| LED burns out quickly | Add a resistor between the battery and LED to limit current. |