🧭 Plot Summary
A sound wave is a traveling disturbance in air pressure — a vibrating object pushes on the air next to it, that air pushes the next bit of air, and the disturbance keeps handing itself forward until it reaches your ear. It isn't a physical object moving through the room; it's a pattern moving through a medium.
Three numbers describe any wave completely: wavelength(λ, the distance of one full repeating pattern), frequency (f, how many repeats happen per second, in Hz), and period(T, how long one repeat takes). They're connected by one equation, v = fλ, that works for every wave you'll ever study — sound, light, water, all of it.
What you will do in this lesson
- Meet the three numbers that describe any wave: wavelength, frequency, and period.
- Learn the one equation that ties them together: v = fλ.
- Discover that sound is a longitudinal wave — and why the wavy graphs you'll draw don't look like the actual motion of the air.
- Practice reading wavelength directly off a pressure-vs-position graph.
- Build the vocabulary that Lesson 3-1-2 needs to connect frequency to pitch and amplitude to loudness.
Why it matters
Project 3-1-3: Garage Band asks you to build and tune a real instrument — and tuning is nothing more than adjusting length or tension until a wave's frequency lands where you want it. This vocabulary is what makes that possible instead of guesswork.
✅ Self-Check Before You Roll On
Check off each item as you get there. These are not grades — they are your own signal.