Science 4: Light Waves
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When light waves, what should you do? Wave back of course. You don't want to be impolite. Today's video is all about light waves.
|Elementary and Middle School||4th Grade|
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]
We're talking about light waves.
Light is actually a form of energy called electromagnetic radiation. [Coop pointing at a blackboard]
But don't worry: just because the word "radiation" is in there doesn't mean you need to wear
a hazmat suit every time you flip on a light switch. [Boy turns off the light and glows in the dark]
Though that would look pretty cool….
Just like sound, light also travels in waves.
And just like sound waves, light waves are measured in hertz. [Lamp is turned on and a lightwave is emitted]
But there are some pretty big differences between those kinds of waves. [Man holding a starting gun at an athletics track]
For one, light waves are way, way faster than sound waves. [Light wave is much faster than the soudwave]
In fact, they're so fast that when we measure light waves, we need to add new prefixes to
So although a sine wave might clock in with a frequency of 220 Hz… [The sine wave is shown]
…a wave of red light comes in at 448 tetrahertz.
Or, said as a number with way more zeros, 448 trillion hertz. [Dino pointing at a blackboard]
As you might imagine, light waves and sound waves don't really race too often.
It'd just be embarrassing… [Broken radio that is sparking and smoking]
When we talk about light, we generally mean the kind of light we can see, aka all those
lovely colors that make up the rainbow. [Rainbow behind palm trees]
Visible light has frequencies that range between about 400 and 800 tetrahertz.
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]
And it turns out, there are also kinds of light we can't see.
Ultraviolet radiation has a higher frequency than visible light… [UV radiation hitting the surfer]
…while infrared radiation has a lower frequency. [Infrared camera showing the heat of a person]
So if you were thinking of becoming an artistic sensation by only painting in ultraviolets
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]
But hey, what do we know?
Hipsters go for some pretty weird stuff… [Woman taking a picture of the blank painting]
And light just doesn't just come out of nowhere.
One of the biggest sources of light is the sun. [The sun]
It has it all: visible light, ultraviolet rays, infrared rays. [The sun emitting the different waves]
Whatever you want, the sun's got you covered.
Of course, it does have that nasty habit of disappearing when our planet does just a bit
too much rotating, but just because the sun's gone doesn't mean you have to be left in the [Surfer looks disappointed]
Electric light is a great source of light.
Or, if you want to take the traditionalist route… [A fire on the beach]
…there's always fire.
Just make sure you don't mix your light sources.
Lamps and bonfires aren't exactly the best of friends… [Lamp crashes into the fire and surfer runs away]