How can we make a rainbow?

You can make beautiful rainbows with flashlights and water. It's simple!

1) Toolbox: a mirror, a tray, a flashlight, a piece of white paper and water;

2) Game DIY: Inject a proper amount of water into the rectangular tray, and then lean the mirror against one side of the rectangular tray; Turn on the flashlight to illuminate the submerged part of the mirror; Put the white paper in front of the mirror so that the light can be reflected on the white paper. Observing the white paper, we find that the rainbow has seven colors: red, orange, yellow, green, blue, purple.

3) Science in the game: The light of the flashlight looks white, but it is actually composed of seven different colors and different wavelengths of light: red, orange, yellow, green, cyan, blue and purple. The flashlight shines on the mirror and is reflected by the mirror. The reflected light returns in the same way and refracts when it passes through the water layer. Seven colors of light are refracted to form different angles, penetrate the water surface at different positions, and shoot on white paper, thus forming a beautiful rainbow.