Placeholder Image

Subtitles section Play video

  • Hi Folks! Here's a fun, short science video showing how to use a prism

  • to separate sunlight into a rainbow of colors. As you can see, with a little work and a sunny

  • day you can get a pretty nice result.

  • I bought this prism at a local store called Focus Scientific

  • that sells telescope and other optical equipment. It's a simple five sided piece of glass with

  • three sides forming a triangle.

  • To demonstrate it in action I have this board on a tripod so I can

  • arrange it any way I want. On top I've tape these two pieces of cardboard

  • with a small gap between them.

  • I start by allowing only a thin slit of sunlight to go through this gap.

  • That's to make sure that most of the light I'm using is coming from one direction only.

  • As you can see, even with this paper far away, this light appears white on the paper.

  • Now I put my prism in the way of the light. You'll notice that the light no longer continues

  • in a straight line. And it you look closely you can see all the

  • visible colors that that sunlight is made up of.

  • I'll be talking only about visible light in this video.

  • Having found a good location for the prism, I tape it in place.

  • How does it work?

  • Visible light is made up of multiple electromagnetic waves with different wavelengths.

  • Those wavelengths represent different colors, red, orange, yellow, green, blue, indigo and

  • violet. On this side of the prism they're all overlapping

  • and going in the same direction. But when they cross the boundary between the

  • air and the glass of the prism, they bend. This bending is called refraction.

  • When they exit the prism, going from glass to air, they bend again.

  • The key is that the amount they bend by is different because of the different wavelengths,

  • or colors.

  • The result is that red light will bend something like this when entering the prism,

  • and like this when exiting the prism. But violet light will bend something like

  • this when entering the prism, and like this when exiting the prism.

  • So they enter going in the same direction but leave going in different directions.

  • And when we put this paper in the way of the light,

  • we see the different colors separated. Putting the paper on a slant helps spread

  • it across more area, so we can see the colors more clearly.

  • And that's how a prism works to make a rainbow of colors.

  • What if you don't have a fancy tripod or prism? Get a box instead and tape some white paper

  • to the top along with the two pieces of cardboard for

  • the gap. Fill a plastic or glass container with water,...

  • and use that to bend the light. It may not be as good as a prism but you'll

  • see some color separation at the edges.

  • Well thanks for watching!

  • See my youtube channel, rimstarorg, for more fun science videos like this.

  • That includes another where I show how this same refraction is used

  • by a Fresnel lens to focus light, along with some experiments.

  • Another short, fun one on how fast an electron and electricity move down a wire.

  • And for variety, how to make a portable crystal radio in a pizza box.

  • And don't forget to subscribe if you like these videos,

  • or give a thumbs up or leave a question or comment below.

  • See you soon!

Hi Folks! Here's a fun, short science video showing how to use a prism

Subtitles and vocabulary

Click the word to look it up Click the word to find further inforamtion about it