Summary
Introduction
Build your own mini LED lightsaber with a straw in this quick Star Wars-themed STEM activity. May the Force be with you!
Materials
- Electrical tape
- Scissors
Prep Work
- Coin cell batteries are dangerous if swallowed. Keep them away from small children and pets.
Instructions
- Cut your straw into two pieces to form the blade and handle of your lightsaber.
- Pinch the legs of the LED so they squeeze the two faces of the battery. The long leg of the LED should touch the positive (+) side of the battery. The LED should light up. If it does not light up, you probably have the LED backwards. Try flipping it around.
- Tape one of the LED legs to one side of the battery. Make sure there is a gap between the other side of the battery and the other leg, so the LED only turns on when you squeeze them together. Notice the gap in the picture.
- Press the battery and both LED legs into the shorter piece of straw (the handle). Be careful that the tape does not slide off the LED leg. It can help to use something (like the scissors or a pencil) to press the battery down into the straw. Press until the bottom of the LED is flush with the top of the straw.
- Squeeze the straw where the battery is, and the LED should light up.
- Slide the longer piece of straw (the blade) over the top of the LED.
- Wrap the handle and connection between the two straw pieces in electrical tape.
- Squeeze the handle to light up your mini LED lightsaber!
What Happened?
When you connected the LED to the battery, you made a very simple circuit. LEDs only let electricity flow through them in one direction, which is why they will not light up if you connect them backwards. Many times, circuits with LEDs require another part called a resistor, but you do not need a resistor when using a coin cell battery. See the Digging Deeper section to learn more.
Digging Deeper
Many electronics projects use breadboards for building circuits with LEDs, and the circuits in these projects frequently require AA, AAA, or 9V batteries. These batteries can provide a lot of electrical current—so much that they will quickly burn out the LED (or even cause it to explode!) if it is connected directly to the battery. To prevent this, we use an extra part called a resistor. It "resists" the flow of electrical current and limits the amount of current flowing, keeping it to safe levels for the LED.
Coin cell batteries cannot provide as much current as AA, AAA, or 9V batteries. They have a much higher internal resistance. This limits the amount of current that can flow, even when you connect an LED directly to the battery. This makes it safe to build a simple circuit without a separate resistor, making it convenient for you to build a compact circuit that fits directly into the handle of your lightsaber!
Ask an Expert
For Further Exploration
- What is your favorite color lightsaber from the Star Wars series? Try making different-colored lightsabers using different-colored LEDs and straws. Time for a light-side vs. dark-side battle!
- Try using two LEDs to build a dual-bladed lightsaber (Hint: you still only need to use one battery).
