English: Rainbow.

Rainbow. (Photo credit: Wikipedia)

The Term Refraction Means What In Terms of Rainbows?

Refraction is a description of the bending of light through raindrops to create rainbows.

But, you don’t have to wait for a rainstorm to end and the sun to come out to make your own rainbows.

And, you don’t have to have a prism.

You will still, however, need a sunny day.

Materials:

  • Water
  • White paper
  • Glass
  • Sunny window

Optional:

  • Milk
  • Lemonade powder mix
  • Flashlight
  • Bowl of water

Instructions:

  • Fill the glass about 2/3 full with water
  • Hold the glass up to a sunny window
  • Hold the white piece of paper at a slight angle under and to the side of the glass.

What Should Happen?

As soon as you get the angle right, you will see a rainbow-colored reflection on the white paper.

Why Is This Happening?

The light through the sunny window is refracting through the water, or separating, to show the different colors that make up a beam of light.

The Term Refraction Means What in Terms of Rainbows?

White light, as scientists call it, or what we see as invisible light from the sun, separates into the different colors that make up white light when it crosses a boundary over which the different colors of light travel at different speeds.

Light travels faster through air than water.

When it hits the boundary between them, the different colors of light cross that boundary at different speeds.

This is called Snell’s Law, or the law of refraction.

White light separates into its respective colors by changing direction when crossing a boundary of two mediums in which it travels at different speeds.

Refraction is the change in direction of light when it crosses the medium.

Since the different colors are crossing at different speeds, when they change direction at the boundary of the air and water, they come out producing a rainbow.

Optional Experiments:

Does light create rainbows with other liquids, or just with water?

How about if the room is dark instead of sunny?

Instructions:

  • Fill glass with milk and repeat experiment with white paper.
  • Fill glass with water, then add, one teaspoon at a time, powdered lemonade mix and repeat experiment with white paper.
  • Fill glass bowl with water in a dark room. Shine a flashlight through the water onto a wall.

I did not get any rainbow with milk, which kept the light from traveling through it.

With lemonade powder, I continued to get rainbows, though lighter and lighter, until I had added four teaspoons of powdered lemonade.

You can also do this experiment in a dark room.

Fill a round bowl with water. Turn out all the lights.

Shine a flashlight through the bowl of water onto a light wall.

A rainbow will appear on the wall.

You can also see a rainbow through a feather.

Hold the feather in front of a lit candle and squint through the soft, fuzzy feathers at the candlelight.

You will see the colors of the rainbow around the edges of the flame.

Thanks to sciencekids.co.nz for the sunny day activity.

Thanks to geekmom.com for the dark room activity.

Thanks to good-science-fair-projects.com for the feather activity.

Carol Covin, Granny-Guru

Author, “Who Gets to Name Grandma? The Wisdom of Mothers and Grandmothers

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