Rocket draws a wavy line across the whiteboard in the garage. "Ta da! A wave!"
Raven draws a second wave under it. Hers has taller hills and the hills are farther apart.
"Both are waves," she says. "What do you notice that is different?"
Rocket tilts his head. "Mine is shorter... and squished?"
Nova projects a glowing ruler between the two drawings. "Here is a clue," she says. "Measure up and down. Then measure side to side."
The top of a wave is the crest. The bottom of a wave is the trough.
Amplitude is the height of a wave. A tall wave has a big amplitude. A short wave has a small amplitude.
Wavelength is the spacing between wave peaks. Measure it from one crest to the next crest.
Waves of the same type can have different amplitudes and different wavelengths.
| Word | Where to look |
|---|---|
| Crest | The top of a wave |
| Trough | The bottom of a wave |
| Amplitude | How tall the wave is |
| Wavelength | From one crest to the next crest |
To compare amplitude, look at how tall each wave is.
To find wavelength, measure from one crest to the next crest.
Use the same ruler for every wave so the numbers are fair.
Scientists use these measurements to compare waves.
| Statement | True or false? |
|---|---|
| The crest is the bottom of a wave. | ? |
| Amplitude tells how tall a wave is. | ? |
| Wavelength is measured from crest to crest. | ? |
| All waves have the same wavelength. | ? |
You can describe waves like a scientist now. Tomorrow you make your own waves!