Watch a wave roll across the ocean — what is actually moving? Let's investigate.
Four ordinary scenes. In each one, something looks like it's traveling. Click each card and watch what's really going on.
Let's slow it down. Watch carefully. What happens as the pulse moves through the row?
Not the particles. They each lifted up and dropped back down. What moved from one end to the other was energy — a disturbance passing through the row. Scientists call that traveling disturbance a wave.
Two astronauts float in space. Their helmets are inches apart. Make a prediction for each question.
Some waves need a medium — stuff to travel through, like water, air, or a row of particles. Sound is one of these.
But light is different. Light is an electromagnetic wave, and electromagnetic waves don't need anything at all. They can travel through completely empty space.
That's why sunlight reaches Earth in about 8 minutes — even though there's nothing between the Sun and us for it to travel through.
Same speaker. Two different rooms. Watch carefully.
Sound is a mechanical wave. Mechanical waves need stuff to travel through — that stuff is called a medium. The wave moves forward by making particles vibrate against the next particle, and the next, and the next.
No medium means no neighbors to pass the energy to. No neighbors means no wave. That's why space is silent.
We now know waves carry energy. To measure that energy, scientists need a language for describing wave shapes. Let's learn the first three words.
Compare these two waves. Same height. Different something. What do you notice?
Scientists call the distance from one peak to the next peak the wavelength. It's measured side-to-side, along the wave.
Two waves travel toward the gold line. When you press Start, watch the line for one second. Count the crests that cross it.
The number of crests that pass a point in one second is called the frequency of the wave. Scientists measure it in Hertz (Hz).
If 2 crests pass in one second, the wave's frequency is 2 Hz. If 5 crests pass in one second, that wave's frequency is 5 Hz. Higher frequency just means more passes per second.
Two ocean waves. Same distance between peaks. One is much bigger than the other.
The height of a wave from the resting line to the crest is called its amplitude. The bigger the amplitude, the more energy the wave carries.
A small amplitude wave gently bobs your boat. A huge amplitude wave can sink it. Same kind of wave — totally different amount of energy.
You've met all three. Now let's see how they fit together — by trying something.
Drag the slider. The wave updates live. Watch all three readouts.
Wavelength and frequency are inversely linked. If the peaks get closer together, more of them pass a point each second — so frequency goes up. There's no way to shrink one without raising the other.
For electromagnetic waves like light, higher frequency is also associated with higher energy. (Amplitude still controls the energy of mechanical waves like sound — both rules are true; they just apply to different kinds of waves.)
A new wave. Five terms. Show what you know — pick a word, then click where it belongs on the wave.
Take the quiz to lock in what you've learned.
Use these terms to jump back to where each idea was explained. Some links may reveal hidden explanations so you can review them.
10 questions covering everything you discovered. Answer every question, then submit.
You've started the Waves unit. Three experiences coming up next will let you go deeper into what you just discovered.