The Wave on a String simulation from PhET lets you make waves on a string by moving its end by hand or by using an oscillator. You can change the frequency, amplitude, damping and tension, choose how the end of the string behaves, and even watch the string vibrate in slow motion. It is free, runs in any browser on a phone, tablet or laptop, and it is a great fit for the waves and sound lessons in Tamil Nadu State Board (Samacheer Kalvi) Science and Physics.
What is the Wave on a String simulation?
This interactive simulation lets you explore how waves travel along a string. You can make waves by moving the end of the string yourself or by setting an oscillator, and you can see what happens when a wave reaches the end of the string. Because it runs on HTML5, there is nothing to install, and it works on phones, tablets, Chromebooks and computers.
Middle school to university
Waves, frequency, amplitude, damping and reflection
Phone, tablet, Chromebook, PC
English
PhET’s learning goals are to discuss wave properties using common vocabulary, and to predict how waves behave in different media and at reflective endpoints.
Launch the Wave on a String simulation online
Tap or click inside the player and start exploring. Use the full-screen button in the player for a bigger view.
Credit: University of Colorado Boulder
How to use the Wave on a String simulation, step by step
- Predict first. Before you make a wave, say how you think it will move along the string.
- Make a wave by hand. Move the end of the string up and down and watch the wave travel.
- Use the oscillator. Set the frequency and the amplitude and compare the waves you get.
- Change damping and tension. See how a wave fades and how the speed changes.
- Change the end of the string. Try a fixed end, a loose end and an open end, and watch the reflection.
Tip for students: change only one setting at a time. That is how you find out what each one does to the wave.
The idea behind the simulation: v = f × λ
v = f × λ
Here v is the wave speed in metres per second (m/s), f is the frequency in hertz (Hz) and λ (lambda) is the wavelength in metres (m). The period is the time for one full wave, T = 1 ÷ f. On a string, the speed depends on the string itself: a tighter string makes the wave travel faster.
Worked example: A wave has a frequency of 2 Hz and a wavelength of 1.5 m. Its speed is 2 × 1.5 = 3 m/s, and its period is 1 ÷ 2 = 0.5 s.
Wave key terms explained
These are the words you will meet while using the Wave on a String simulation, with simple meanings.
Wave
A disturbance that carries energy from one place to another.
Amplitude
The biggest displacement of the string from its rest position.
Frequency
The number of waves that pass a point each second, in hertz (Hz).
Wavelength
The distance between two matching points on neighbouring waves.
Wave speed
How fast the wave travels along the string.
Damping
The loss of energy that makes a wave slowly fade.
Tension
How tightly the string is pulled.
Reflection
A wave bouncing back when it reaches the end of the string.
Transverse wave
A wave where the string moves at right angles to the direction the wave travels.
Common mistakes: Thinking the string itself travels along with the wave, mixing up amplitude and wavelength, and forgetting that a higher frequency gives a shorter wavelength when the speed stays the same.
Try the wave speed calculator (practice what you explore)
Enter a frequency and a wavelength to find the wave speed and the period. Then tap a “what if” button.
What happens when you change a variable
| Change | Effect on the wave |
|---|---|
| Higher frequency (same speed) | Shorter wavelength |
| Larger amplitude | Taller waves that carry more energy |
| Higher tension | The wave travels faster |
| More damping | The wave fades faster |
| Fixed end | The wave reflects upside down |
| Loose end | The wave reflects the right way up |
Classroom activities for teachers
The Wave on a String simulation fits a single 40-minute period.
- Predict and test (10 min): students predict what happens when the frequency or the amplitude changes, then check.
- Measure the wave (10 min): students estimate the wavelength and frequency and calculate the speed.
- End of the string (10 min): students compare what happens at a fixed end and at a loose end.
- Exit ticket (10 min): students explain in two sentences the difference between frequency and amplitude.
Looking for the matching chapters? Browse the Science and Physics books on TN SchoolBooks and download the Samacheer Kalvi PDFs, then use this simulation to make the waves and sound lessons visual. More free science simulations and textbook PDFs are on the home page.
Quick quiz: test your understanding of waves
Score: 0 / 5
Wave on a String simulation: frequently asked questions
Is the Wave on a String simulation free?
Yes. PhET simulations are free to run online in a browser. Check PhET’s licensing page for reuse terms.
Does it work on a mobile phone?
Yes. It is built with HTML5 and works on phones, tablets and Chromebooks. Use landscape mode or the player’s full-screen button for a bigger view.
What is the difference between frequency and amplitude?
Frequency is how many waves pass a point each second. Amplitude is how far the string moves from its rest position. Frequency changes how fast the string wiggles, while amplitude changes how big the wave is.
What happens when a wave reaches the end of the string?
The wave is reflected. At a fixed end the reflected wave comes back upside down. At a loose end it comes back the right way up.
The Wave on a String simulation turns an invisible motion into something you can start, slow down and see. Explore it, take the quiz above, and keep experimenting until predicting a wave feels easy.