Isaac Newton is credited with being the first person in history to demonstrate that white light is made up of all the colors present in the visible spectrum. He also demonstrated that this light can be divided into different colors thanks to a process called refraction. In order to refract light, he made use of a prism, but water can also be used to observe this phenomenon. The product of refracted white light will be a rainbow, just like those seen in the sky.
Method 1 of 3: Refracting light with a prism
Step 1. Take a prism
There are different types of prisms that manipulate light in different ways. Here, you will need a refractory prism. This type will allow you to distort the light in such a way as to divide it based on the frequency of the light waves. In other words, waves with a shorter frequency will be more distorted, as well as those with a longer frequency will have less distortion. This creates a rainbow as light passes through the prism.
You can buy a prism at science supply stores, hobby stores, or online. Basic prisms are also relatively inexpensive
Step 2. Find a sunny spot
The prism works by splitting the beam of white light into its component colors. To see this in practice, you need a high-intensity light source. It is best to place the prism in a sunny window or outside on a day with strong sun.
Step 3. Let the light pass through the prism
It is important that there is nothing stopping the light from reaching the prism. As it passes, it will distort and split into a rainbow. It may be easier to see this phenomenon if you aim the prism at a wall or white colored paper.
Method 2 of 3: Passing Light Through a Mist
Step 1. Find a water source
Typically, rainbows are seen on rainy days. This is because there are many water droplets falling across the sky that refract sunlight. To simulate this phenomenon, you must find a water source that can be moved. Either a hose or a small spray bottle will work.
Step 2. Create the fog
A flow of running water is not ideal for creating a visible rainbow. Instead, you should make a water mist that sunlight needs to pass through. You can create it by pressing the hose outlet with your thumb or rotating it to the spray position.
Step 3. Rotate the mist to catch sunlight
Once a constant mist has formed, rotate it so that sunlight passes through it directly. This will allow the refraction of these solar rays by small droplets of water. That way you'll see the rainbow form in the mist.
Method 3 of 3: Passing Light Through Standing Water
Step 1. Fill a clear glass with water
Get a glass with smooth edges. Colored, textured or patterned glass will yield different results. Fill the glass to the brim and try not to spill any water.
Alternatively, you can pour the water into a bathtub or other container. Next, place a mirror inside it and immerse it keeping it at a 45° angle
Step 2. Let the light pass through the glass
It must enter through the top of the glass and reach the surface of the water directly. It will then move to the other side of the glass, and a rainbow will be visible. Water causes light to be refracted the way a prism would.
Step 3. Use a backdrop to increase visibility
If you are having trouble seeing the rainbow, position the glass so that it glows on a wall or white piece of paper. This protection will make it easier to see the rainbow. You can use other colors, but the result may not be as effective.