In this activity students make circuits with LEDs, conductive copper tape, and 3V “coin” batteries. The circuits can be incorporated into greeting cards or art projects
Students will build series and parallel circuits.
For each participant:
50 cm adhesive copper tape, 6 mm width (Sources rp electronics, or SparkFun Electronics)
one piece of paper about 10 cm square
one 3V coin battery, size 2032 or CR1220
one or two LEDs
one binder clip
coloured paper and art supplies for making a card
What To Do
- Remind students of the essential parts of a circuit: there must be an energy source and a path for the current to follow through the resistance. The circuit must form a circular path from the energy source (battery) through the resistance and back to the source.
- Explain that the path in this circuit will be made of copper tape.
- Have students draw a square path on the paper to represent the circuit, noting where the light will be and where the battery will be.
- Check the path for completeness before giving students the copper tape.
- Students use the tape to cover the path they have drawn, leaving a space for the LED bulb and for the battery.
- Demonstrate that the coin battery has a positive and a negative side. Show students that the long lead of the LED must connect to the positive side of the battery and the short end must connect to the negative side.
- Students can now use regular adhesive tape to attach their LED to their circuit.
- Finally, students should fold the paper so that one end of the circuit connects to the positive side of the battery and one end to the negative side. The binder clip holds the battery in place so that the bulb stays on. These photos show the finished product.
- Once the circuit is functional, students can create a card. The students can make their own designs or you can offer some suggestions. Imagine something that includes a light – it could be a car headlight, a candle on a cake, the eye of a bird or an animal, a light in a house window or even a star in the sky. Draw the design on coloured paper and make a hole for the LED bulb to poke through.
- Attach the paper circuit behind the artwork to complete your card. The photos above show the front and back of a very simple card.
- Older or more experienced builders may want to use two LED bulbs. These usually must be wired in parallel (see “Template for two LEDs in parallel” in Weekend Program – Playful Circuits Templates.docx) If you put two in series there is typically not enough power to light both. Note: If you use two LEDs of different colours, sometimes only one LED will light (the one with the lowest resistance). Two LEDs of the same colour work well.
Science World Resources | Full Unit | Playful Circuits