ShmoopTube

00:04

[Dino and Coop singing]

00:13

When we go to the beach on a bright, sunny day, we're probably focused on those big,

00:17

rolling ocean waves. [Surfer with his board]

00:18

But guess what?

00:19

There are plenty of other waves knocking around out there. [Surfer has sunblock on his nose]

00:21

And no, we don't mean that cute lil' sea lion that keeps waving at us….aww… [Sea lion waving asking for someone to put suncream on it's back]

00:25

We're talking about light waves.

00:27

Light is actually a form of energy called electromagnetic radiation. [Coop pointing at a blackboard]

00:29

But don't worry: just because the word "radiation" is in there doesn't mean you need to wear

00:33

a hazmat suit every time you flip on a light switch. [Boy turns off the light and glows in the dark]

00:35

Though that would look pretty cool….

00:38

Just like sound, light also travels in waves.

00:40

And just like sound waves, light waves are measured in hertz. [Lamp is turned on and a lightwave is emitted]

00:42

But there are some pretty big differences between those kinds of waves. [Man holding a starting gun at an athletics track]

00:46

For one, light waves are way, way faster than sound waves. [Light wave is much faster than the soudwave]

00:49

In fact, they're so fast that when we measure light waves, we need to add new prefixes to

00:53

hertz.

00:54

So although a sine wave might clock in with a frequency of 220 Hz… [The sine wave is shown]

00:57

…a wave of red light comes in at 448 tetrahertz.

01:01

Or, said as a number with way more zeros, 448 trillion hertz. [Dino pointing at a blackboard]

01:06

As you might imagine, light waves and sound waves don't really race too often.

01:10

It'd just be embarrassing… [Broken radio that is sparking and smoking]

01:11

When we talk about light, we generally mean the kind of light we can see, aka all those

01:15

lovely colors that make up the rainbow. [Rainbow behind palm trees]

01:18

Visible light has frequencies that range between about 400 and 800 tetrahertz.

01:22

Luckily for us, you don't need to be too good at calculating frequencies to enjoy a good [Women taking a picture of a double rainbow]

01:26

rainbow.

01:27

And it turns out, there are also kinds of light we can't see.

01:30

Ultraviolet radiation has a higher frequency than visible light… [UV radiation hitting the surfer]

01:32

…while infrared radiation has a lower frequency. [Infrared camera showing the heat of a person]

01:35

So if you were thinking of becoming an artistic sensation by only painting in ultraviolets

01:38

and infrareds, we'd recommend you save some time and just ditch those plans. [Man looking proud of his painting, but the canvas is blank]

01:42

But hey, what do we know?

01:43

Hipsters go for some pretty weird stuff… [Woman taking a picture of the blank painting]

01:45

And light just doesn't just come out of nowhere.

01:47

One of the biggest sources of light is the sun. [The sun]

01:50

It has it all: visible light, ultraviolet rays, infrared rays. [The sun emitting the different waves]

01:53

Whatever you want, the sun's got you covered.

01:55

Of course, it does have that nasty habit of disappearing when our planet does just a bit

01:59

too much rotating, but just because the sun's gone doesn't mean you have to be left in the [Surfer looks disappointed]

02:02

dark.

02:03

Electric light is a great source of light.

02:05

Or, if you want to take the traditionalist route… [A fire on the beach]

02:07

…there's always fire.

02:08

Just make sure you don't mix your light sources.

02:10

Lamps and bonfires aren't exactly the best of friends… [Lamp crashes into the fire and surfer runs away]

Full Transcript