Newton discs, How do they work?

Sunlight has no color, that's why it is known as white light. In fact the white light is a mix of different colors, these colors are visible only when light passes through a transparent object such as glass, and decomposes in all colors, this effect is commonly called rainbow and scientifically called spectrum.

The spectrum consists of seven colors:

• red; 
• orange; 
• yellow; 
• green; 
• blue; 
• indigo; 
• violet.  

Today we will do a "magic disc"- the Newton disc. We will learn that white light is made by mixing all these 7 colors.

What we need:

• pencil,
• scissors,
• thick white card,
• crayons, markers will do,
• ruler,
• compass,
• protractor.

How to:

1. Cut the card in a circle, use a compass;
2. Use the protractor to divide it into 7 parts, like in the picture, sections of 55 º, 60 º and 35 º;
3. Paint each piece with a spectrum of colors, the figure shows the red, the orange, the yellow, the green, the blue, the indigo and the violet. Paint it as uniformly as possible and use the same intensity with all the colors;
4. Make a hole in the middle of the circle and pass the pencil through it, the center of the circle is where the "hole" of the compass is;
5. Spin the pencil quickly, like a top, look at the color wheel, adjust as necessary to rotate the set easily.

What happens?
The disc appears as a grayish white tone.

Why?
In fact if the conditions were optimized we would see a clean white circle, without the grayish tone.

The colors painted on the wheel are the main colors of the white light, like those that are present in the rainbow. When the wheel spins it creates a visual effect that makes your brain believe that they mingle and wheel appears white when in reality it´s multicolored.

This is a demonstration, turn the test in to an experiment, experiment with different color combinations. Here are two suggestions: red, blue and green, or red and green for example, what happens? Why?

Et Voila!
After all the white has a lot of color

Enjoy it!