This is a recording of a recent live teleclass I did with thousands of kids from all over the world. I've included it here so you can participate and learn, too!
This class is all about Light Waves! Energy can take one of two forms: matter and light (called electromagnetic radiation). Light is energy in the form of either a particle or a wave that can travel through space and some kinds of matter, like glass.
We're going to investigate the wild world of the photon that has baffled scientists for over a century. We'll also do experiments in shattering laser beams, bending and twisting light, and also split light waves into rainbow shadows. Materials:
The ripples are like light. Notice the waves are not really moving the water from one side of the pond to the other, but rather move energy across the surface of the water. To put it another way, energy travels across the pond in a wave. Light works the same way – light travels as energy waves. Only light doesn't need water to travel through the way the water waves do - it can travel through a vacuum (like outer space).
Light can change speed the same way sound vibrations change speed. (Think of how your voice changes when you inhale helium and then try to talk.) The fastest light can go is 186,282 miles per second – that's fast enough to circle the Earth seven times every second, but that's also inside a vacuum. You can get light going slower by aiming it through different gases. In our own atmosphere, light travels slower than it does in space.
Your eyeballs are photon detectors. These photons move at the speed of light and can have all different wavelengths, which correspond to the colors we see. Red light has a longer wavelength (lower energy and lower frequency) that blue light.
For example, if you stick a pencil is a glass of water and look through the side of the glass, you'll notice that the pencil appears shifted. The speed of light is slower in the water (140,000 miles per second) than in the air (186,000 miles per second), called optical density, and the result is bent light beams and broken pencils.
You'll notice that the pencil doesn't always appear broken. Depending on where your eyeballs are, you can see an intact or broken pencil. When light enters a new substance (like going from air to water) perpendicular to the surface (looking straight on), refractions do not occur.
However, if you look at the glass at an angle, then depending on your sight angle, you'll see a different amount of shift in the pencil. Where do you need to look to see the greatest shift in the two halves of the pencil?
Depending on if the light is going from a lighter to an optically denser material (or vice versa), it will bend different amounts. Glass is optically denser than water, which is denser than air.
Not only can you change the shape of objects by bending light (broken pencil or whole?), but you can also change the size. Magnifying lenses, telescopes, and microscopes use this idea to make objects appear different sizes.
This class is all about Light Waves! Energy can take one of two forms: matter and light (called electromagnetic radiation). Light is energy in the form of either a particle or a wave that can travel through space and some kinds of matter, like glass.
We're going to investigate the wild world of the photon that has baffled scientists for over a century. We'll also do experiments in shattering laser beams, bending and twisting light, and also split light waves into rainbow shadows. Materials:
- laser pointer
- flashlight
- paper clip
- gummy bear (green and red)
- old CD
- paper clip
- rubber band
- pond water (just a little bit)
Key Concepts
Imagine tossing a rock into a still pond and watching the circles of ripples form and spread out into rings. Now look at the ripples in the water - notice how they spread out. What makes the ripples move outward is energy , and there are different kinds of energy, such as electrical (like the stuff from your wall socket), mechanical (a bicycle), chemical (a campfire) and others.The ripples are like light. Notice the waves are not really moving the water from one side of the pond to the other, but rather move energy across the surface of the water. To put it another way, energy travels across the pond in a wave. Light works the same way – light travels as energy waves. Only light doesn't need water to travel through the way the water waves do - it can travel through a vacuum (like outer space).
Light can change speed the same way sound vibrations change speed. (Think of how your voice changes when you inhale helium and then try to talk.) The fastest light can go is 186,282 miles per second – that's fast enough to circle the Earth seven times every second, but that's also inside a vacuum. You can get light going slower by aiming it through different gases. In our own atmosphere, light travels slower than it does in space.
Your eyeballs are photon detectors. These photons move at the speed of light and can have all different wavelengths, which correspond to the colors we see. Red light has a longer wavelength (lower energy and lower frequency) that blue light.
What's Going On?
When a beam of light hits a different substance (like a window pane or a lens), the speed that the light travels at changes. (Sound waves do this, too!) In some cases, this change turns into a change in the direction of the beam.For example, if you stick a pencil is a glass of water and look through the side of the glass, you'll notice that the pencil appears shifted. The speed of light is slower in the water (140,000 miles per second) than in the air (186,000 miles per second), called optical density, and the result is bent light beams and broken pencils.
You'll notice that the pencil doesn't always appear broken. Depending on where your eyeballs are, you can see an intact or broken pencil. When light enters a new substance (like going from air to water) perpendicular to the surface (looking straight on), refractions do not occur.
However, if you look at the glass at an angle, then depending on your sight angle, you'll see a different amount of shift in the pencil. Where do you need to look to see the greatest shift in the two halves of the pencil?
Depending on if the light is going from a lighter to an optically denser material (or vice versa), it will bend different amounts. Glass is optically denser than water, which is denser than air.
Not only can you change the shape of objects by bending light (broken pencil or whole?), but you can also change the size. Magnifying lenses, telescopes, and microscopes use this idea to make objects appear different sizes.
Questions to Ask
- Can light change speeds?
- Can you see ALL light with your eyes?
- Give three examples of a light source.
- Why does the pencil appear bent? Is it always bent? Does the temperature of the water affect how bent the pencil looks? What if you put two pencils in there?
- What if you use oil instead of water for bending a pencil?
- How does a microscope work?
- What's the difference between a microscope and a telescope?
Atoms are too small to see with your eyes, even with a microscope! Atoms themselves do not have different colors (they are clear except under special conditions). Even if you could see the individual atom by itself, it would be way too faint to detect a color.
are atoms different colors?
Oh, no! I am so sorry about that… I’ll get that updated now. You will use those materials also, just later in the section.
I noticed the list of materials are different from the ones outlined in the video. Good thing I checked before I went out to spend extra money!
Which teleclass are you looking for? You should have access to all of them!
Do we have access to the live telecast above? We are doing the light and lazer optics lessons and wondered. Thank you!
Connie Dudley
It depends on your laser (cheaper ones will diffuse the beam out over a given length) and the mirror itself (use front surface mirrors for best results). Most mirrors are back-surface, so the beam has to travel through glass first before it gets reflected, and then it has to go back through the glass again before getting back into the air, which causes losses in the light.
To answer your question, I am trying to do an experiment with lasers and mirrors and also how far a laser can bounce off a mirror in one strait line.
Hmm… what are you looking to do exactly?
Hi, Aroura this is Andie, I have a question for summer e-camp laser lab. Is there a boundery on how far a laser can reflect of an inch long square mirror?
You’re asking two different questions, actually. Are you more wanting to know how light enters your eye and working with the brain to create an image, or why do objects appear the color they are, like a apple being red, the couch being green…?
How does your eye pick up the light around you, like how do you know the couch is green, and stuff like that.
I am not sure which experiment you are referring to. Can you explain a little more or provide the experiment name or url?
for the defracting light expirement does it have to be a green laser because the red one is not working
Flashlights with pictures? I am not quite sure what you mean. Send me a photo or description?
do flashlights with pictures work?