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Make a picture that lights up!
Make a picture that lights up!
Electricity is dangerous! Read this caution.
Materials: One piece of paper, scissors, crayons or pencils, transparent tape, copper tape or aluminum foil, a few LEDs, and one 3V watch battery.
Color a picture (or locate and color a coloring page).
You might try wikimedia commons to locate free coloring books.
Locate one or two sections of the the picture that you would like to light up with LEDs. These sections should be close to each other on the page (i.e., within about six inches)
After coloring your picture, turn it over and locate where your LED(s) should be placed. Mark those with a pencil (or other writing instrument).
To light the LED, we need to create a simple circuit. A circuit is a circular path for electricity to flow. The electricity begins at a power source (e.g., battery), flows through wires to one or more loads (e.g., LEDs, motors, switches) and returns to the battery.
Loads can be placed one after another on the same path in circuits (known as in series), or on separate paths (known as in parallel). Most circuits contain a combination of loads in series and in parallel. Certain loads (e.g., resistors, conductors, diodes) behave differently if placed in series or in parallel.
For LEDs, wiring multiple in a series (one path) divides the power between each LED. This means that the lights will appear dim or may not light at all. Wiring the LEDS in parallel (one path for each LED) provides full power for each LED. This results in brighter lights.
If you want to place two or more LEDs on your picture, we'll have to do it in parallel because we only have 3V batteries. The easiest way to accomplish this is to add two wires running parallel to each other on the back of the picture. Our LEDs will be added to bridge these parallel wires (thus making a unique path to each LED from the battery).
Get a long strip of copper tape, remove the backing and place it by the markings for your LED lights.
Get another piece of tape that is slightly longer than the other. Remove the backing on the tape except for the final inch or so (enough so it can be fold over and touch the first piece of copper tape). Place it parallel to your other piece of copper tape.
Carefully poke holes where your LEDs will be placed.
Image in the Public Domain
Look at an LED:
One lead wire is shorter than the other.
The ridge at the bottom of the bulb has a flat spot above one lead wire (see image).
Each of these conditions identifies the negative lead (cathode)
LEDs work when their positive lead (anode) is connected to the wire from the positive side of a power source and their negative lead is connected to the wire from the negative side of the power source. Determine which piece of copper tape will connect the positive LED lead.
Label which copper wire is associated with the negative and positive LED leads. Then push the LED through the hole and secure the leads to the "wires" with transparent tape.
Caution: Be sure that your negative lead connects to the negative piece of copper tape for each LED. Also be sure that you leave space for your battery to touch the copper wire (not transparent tape) when you secure your leads.
Place the negative pole of the battery on the negative wire. Fold the positive wire to the positive side of the battery. Your LEDs should light. Secure the battery with transparent tape.
Troubleshoot
If your LEDs don't light
Reverse the battery to see if you reversed your LEDs.
Press the tape securing the leads to the copper. Make sure the lead is touching the copper.
Make sure the negative wires or battery sides are not touching positive wires or leads.
Wiggle your LED and see if it lights.
Make sure your battery has power.
Enjoy your picture!
Click to Read What's Happening
Click to Read What's Happening
A direct current circuit is an electric path that forms a circle. Electricity flows from the battery through a wire to various components (e.g., lights, motors, diodes) and back to the battery. The flow of electricity lights the LEDs on your picture.
Watch this YouTube video to see how your circuit works.
If you added more than one light, you likely made a parallel circuit. This ~4 minute video distinguishes between series and parallel circuits.
Look closely at the copper wires on your picture. Notice that they never touch each other directly, even when the battery is connected! Each wire only touches one side of the battery and one LED lead wire. For a circuit to function properly, positive wires should never touch negative wires. If they do, the connection will short your circuit. Short circuits drain batteries quickly and may create heat that can damage your wires.
You can prevent wires from touching each other by adding insulating material between them. Insulating materials do not allow electricity to flow through them easily. Examples of these materials include rubber, paper, plastic, and glass. For paper-based circuits, transparent or masking tape is a good insulator.
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