## Introduction: #STEMontheCheap RGB Light Show Paper Circuit

Let students explore the REAL primary colors and not the lies taught in far too many classrooms. If you ask me, a physicist, what the primary colors are, I would ask you a question. Are you talking about light or paint? The answer is, in fact, different but connected in the most beautiful, symmetric way when it is taught correctly.

In NO case are the primary colors red, yellow, and blue!

The RGB Light Show Paper Circuit will introduce students to the primary colors of light, used for color addition, which are red, green, and blue. It will also introduce them to the secondary colors of light, which you get by mixing combinations of two primary colors together. This demonstration can also be done at full scale using red, green, and blue flood lights with a setup that costs about \$60. When the supplies are purchased in bulk for a classroom, the RGB Light Show Paper Circuits cost under \$1 per circuit.

NGSS Standards

(NOTE: For preschool and early elementary students, the teacher would likely build the RGB Light Show Paper Circuit and the students would use it to make observations, notice, and wonder.)

1-PS4-2 Waves and Their Applications in Technologies for Information Transfer: Make observations to construct an evidence-based account that objects in darkness can be seen only when illuminated.

1-PS4-3 Waves and Their Applications in Technologies for Information Transfer: Plan and conduct investigations to determine the effect of placing objects made with different materials in the path of a beam of light.

4-PS3-2 Energy: Make observations to provide evidence that energy can be transferred from place to place by sound, light, heat, and electric currents.

4-PS3-4 Energy: Apply scientific ideas to design, test, and refine a device that converts energy from one form to another.

4-PS4-2 Waves and Their Applications in Technologies for Information Transfer: Develop a model to describe that light reflecting from objects and entering the eye allows objects to be seen.

MS-PS4-2 Waves and their Applications in Technologies for Information Transfer: Develop and use a model to describe that waves are reflected, absorbed, or transmitted through various materials.

## Supplies

RGB Light Show Paper Circuit Templates

1/4" copper foil tape with conductive adhesive

3 mm LEDs - red, green, and blue

3mm green LEDs (see note below about poor quality green LEDs)

Medium Binder Clips

2032 Button Batteries (Search for these on Amazon. You can usually find them for about 20 cents each when you get them 50 or 100 at a time. Be sure to get them in their own individual blister packs and not in trays. They store better when they are individually sealed in packaging.)

Scissors

Transparent Tape

## Step 1: LED Prep and Warning

LEDs (light emitting diodes) have a negative (short) lead and a positive (long lead). As you can see, the difference in the lengths of the leads is very slight. To ensure you can tell the leads apart, use either scissors or wire cutters to snip off an extra 1/8" off the negative (short) lead, as shown.

Be sure to check your green LEDs using the battery. Sometimes you get good, brilliant green LEDs and other times you get an orange-ish, green LED like the one on the right. You can also check the green LEDs with other colors. If the green lights with the red and yellow LEDs and not with the white and blue, it is a bad one. If it lights a full, brilliant green with the white and blue LEDs, then you have a good quality green LED. In the bulk LED batches where you get five different colors, the green LEDs have often been poor quality LEDs. Replace them with the suggested 3 mm green LEDs you can purchase by themselves in the supply list.

## Step 2: Fold the Corners of the Circuit Template Backward and Then Forward.

This step will set the creases needed later when putting the battery in place. It is easier to first fold the corners backward so you can see the fold line. Then, fold them forward to reset the crease in the correct direction. Open the circuit template up flat to add the copper foil tape.

## Step 3: Cut First Piece of Copper Foil.

Start with the darkest line on the template. Line up the copper foil tape with the backing still on it. Cut the copper foil tape to the correct length, as shown.

## Step 4: Working With Copper Foil Tape and Putting Down First Section.

The best way to get the copper foil tape starting to separate from the backing is by rubbing your finger from the backing forward along the end of the tape, as shown.

Once you have the tape started, DO NOT rip it completely off the backing as you will get a curlicue mess and waste the tape.

Instead, get one end lined up and started then slowly stick the copper foil tape down where it needs to go.

You can use the flat surface of your thumb nail to rub across the copper foil tape to smooth it out and ensure it is fully stuck to the template. Make it a habit of doing this with each section of the circuit.

## Step 5: Cutting the Next Piece of Copper Foil Tape With a 90 Degree Turn.

Next, line the copper tape up on the bottom of the L-shaped section, as shown.

With the backing still on, fold the copper foil tape backward, as shown, and then forward, as shown. This will make it easier to make this 90 degree turn when you are sticking the copper foil tape to the template.

Cut the copper foil tape to the right length.

## Step 6: Putting the Second Piece of Copper Foil Tape in Place.

Get the copper foil tape started off the backing by rubbing your finger along the end.

Put down the first part of the L-shape and then bend the copper foil tape gently backward from the direction it needs to go.

Now, fold the copper foil tape forward and secure it in place along the vertical side of the L-shape.

Use the flat part of your thumbnail to smooth out and fully secure copper foil tape.

NOTE: If you tear the copper foil tape into two sections when working with it, simply pull the tape off and start over with a fresh piece. This will avoid headaches later. Patching sections of copper foil tape or overlapping them to make one section causes inconsistent circuit performance.

## Step 7: Repeat the 90 Degree Technique to Secure Next Piece of Copper Foil Tape.

Use the same techniques from Steps 5 and 6 to align, fold, measure, cut, and secure the next piece of copper foil tape, as shown.

You should now have three sections of the circuit in place.

## Step 8: Next Two Simple Straight Sections.

Measure, cut, and secure the two straight sections which are part of the red circuit.

## Step 9: Using Transparent Tape to Allow for 3-D Circuit Design.

Take a small piece of transparent tape, as shown, and secure it in place where indicated on the template.

## Step 10: Putting Copper Foil Tape Over Top Transparent Tape.

Measure, cut, and secure the section of the circuit which goes on top of the transparent tape, as shown.

## Step 11: Measure and Cut Copper Foil Tape Lengths for Switches.

The line just below the title on the template is exactly the length of copper foil tape needed to make the three switches for the red, green, and blue LEDs. Measure and cut three lengths of copper foil tape using the guide.

## Step 12: Making a Copper Foil Tape Switch.

Take one of the pieces of copper foil tape and line it up with the blue switch section.

Fold the excess copper foil tape back as shown.

Then, fold that section in half onto itself, as shown.

Now, take the backing off the section which is folded onto itself and stick it together to make a tape tag. This tape tag will act as the switch for the circuit.

Finally, take the rest of the backing off of the copper foil tape and secure it in place.

## Step 13: Make the Other Two Switches.

Repeat the procedure in Step 12 to make and secure the switches for the green and red circuits. When you are done, the circuit should look like the one shown.

## Step 14: Step 14: Securing LEDs Into Place.

Set out the three colored LEDs as shown.

NOTE: Be sure to note which direction the negative (short) lead is oriented and which way the positive (long) lead is oriented. If you secure the LEDs backward, they will not light up.

You will need two 3/4" pieces of copper foil tape for each LED. These are laid out on the template but still have their backing on them.

Put the LEDs on top of their locations on the template and secure each lead in place with a 3/4" piece of copper foil tape right on top of the length of tape in that section. The LEDs should be laying on their sides pointing in the direction indicated on the template.

NOTE: Be careful about short circuiting the circuit by allowing either the copper tape sections to become joined or short circuiting the two leads near the LED housing.

## Step 15: Battery Installation and LED Testing.

Place two 2032 button batteries in place, as shown, with the positive side facing up.

Then, fold the corners of the template over on top of the batteries and secure them in place with a medium binder clip, as shown.

Test each LED to ensure it will light when the switches are used to close the circuits. Make certain the green and blue LED will both work at the same time. If they do not, you will need to troubleshoot.

## Step 16: Making the Reflection Box.

Cut out the reflection box template and cut in along the dotted lines, as shown.

Fold along the solid lines and then secure the box with transparent tape.

## Step 17: Exploring Colors Using the Reflection Box.

Place the reflection box over top of all the LEDs.

Turn the lights out in a room which can get fairly dark.

Tinker around with all the color combinations you can create.

Shown are the primary colors of light - red, green, and blue - and also the secondary colors of light which are created by having two LEDs on at the same time. Blue + Green = Cyan (pronounced sigh-ann); Red + Green = Yellow; Red + Blue = Magenta; So, cyan, yellow, and magenta are the secondary colors of light!

What color do you get when all three LEDs are on at the same time?

## Step 18: RGB Light Show Miniature.

As mentioned, the RGB light show can be done using people in front of red, green, and blue flood lights. This can actually be modeled with your \$1 paper circuit.

Set the reflection box up as a screen, as shown.

Turn on one LED and place a pen or slender object between the LED and the screen. Note that the shadow cast is black, as expected.

Turn on two LEDs and now the pen will have two shadows. Note the color of the two shadows is the same as the LEDs which are lit. Also note the color of the screen is now the secondary color created by those two primary colors. In the case shown, green and blue light combining together makes the screen look cyan in color.

Finally, turn on all three LEDs at the same time. Note the color of the three shadows the pen now casts are the secondary colors of light. Yellow where red and green light combine. Magenta where red and blue light combine, and cyan where blue and green light combine.

## Step 19: Extensions: Nature of Science Paper Circuit and Parallel and Series Paper Circuits

If you like this paper circuit, you might also like the Nature of Science Paper Circuit. It can be used to let students discover the rules that govern how LEDs light up together and is a great model for how science really works in so many ways.

If you want students to explore series and parallel circuits, then you will want to check out our Notice, Wonder, Learn Paper Circuits too. These also get into circuit diagrams.

And let's not forget to just let students engineer their own paper circuits. Let them use the science and engineering practices to design their own paper circuits for whatever they would like.

Second Prize in the
Classroom Science Contest