Travelling Waves (Physics)

Lesson notes

Overview

A wave carries energy while the medium only oscillates in place. This topic is rated beginner and is number 37 of 227 in Physics. Core ideas and first intuitions. No prior knowledge needed.

What you are seeing

The panel above shows a wave travelling and interfering, with sliders for frequency and amplitude. The animation is drawn live from the model, so everything you see responds to the sliders. Press Space to pause, use Restart to replay from the start, and change the speed to slow down quick events.

In depth

A travelling wave transfers energy from one place to another while the medium itself just oscillates about its place. In y = A sin(kx − ωt) the amplitude A is the maximum displacement, k = 2π/λ the wave number and ω = 2πf the angular frequency. The pattern moves with speed ω/k. In a transverse wave the oscillation is perpendicular to the direction of travel, as on a string, and in a longitudinal one it is parallel, as in sound.

Reading the relationship

The expression "y = A sin(kx − ωt)" is a compact summary of the idea. It uses the symbols y, A, k, x, ω, t; name what each one stands for before you start. Notice that it contains a trigonometric function, so the result repeats as the angle goes round. Then use the sliders to see how changing one quantity changes the others.

A guided exploration

1. Start with a single wave and measure its wavelength and period. 2. Change frequency and amplitude separately. 3. Add a second source or reflection and watch the waves combine.

Try this

Start by only moving one slider at a time. Say aloud what you expect, then check.

Common pitfalls

Check units and directions first. Many mistakes come from mixing up a scalar with a vector, or from using a formula outside the conditions where it holds.

How it connects

It builds on “Newton’s Law of Gravitation”, the topic before it in Physics. Once you are comfortable, continue with “Wave Speed, Frequency and Wavelength”.

Why it matters

Physics explains how the world moves, heats, shines and interacts, and the same principles power technology around you.

Where you might use it

Revising “Travelling Waves” before a class, exam or certification
Designing vehicles, bridges and devices where motion, forces or waves must be predicted
Understanding how sensors, lasers and communication links actually work
Explaining everyday phenomena such as sound, light, heat and orbits

Frequently asked questions

What is Travelling Waves?

A wave carries energy while the medium only oscillates in place. It is a beginner topic in Physics.

How do I use the Travelling Waves simulation?

The panel at the top shows a wave travelling and interfering, with sliders for frequency and amplitude. Move the sliders one at a time, then press Space to pause the animation and look closer.

What does the formula mean?

The expression y = A sin(kx − ωt) packs the idea into symbols. Name each symbol first, then change one quantity with the sliders and see which others respond.

Who is this topic for?

Core ideas and first intuitions. No prior knowledge needed. If the quiz feels hard, reread the lesson notes and try the previous topic first.

What should I learn before this?

Start with “Newton’s Law of Gravitation”, the previous topic in Physics. Each topic in a subject builds on the ones before it.

How do I track my progress?

Press “Mark as learned” on this page. Progress is stored only in this browser and is never sent anywhere. The Browse page can show topics you have learned or still need to learn.