Ripple Tank Required Practical | GCSE Physics Simulation
Required Practical: Ripple Tank
Freeze the waves with a strobe, use a scale factor to find the real wavelength, and work out the wave speed using v = fλ
v4
This is the pattern on the paper under the tank, which is bigger than the real waves. Drag the two red markers along the ruler to measure. When the picture is still, they snap onto the nearest bright line or card edge.
Live values
Think first: if you make the dipper vibrate faster, what happens to the distance between the waves? Does the wave speed change?
Frequency measured
Scale factor
Distance between markers (on paper)
Stopwatch
Results
Method
Equations
How the pattern is made. A lamp above the tank shines through the water. Each wave crest acts like a lens and focuses the light, so crests show up as bright lines on the paper below and troughs as darker lines. The shadow pattern is bigger than the real waves.
Measuring the frequency. Turn on the strobe and adjust it until the waves appear to stand still: then the flash frequency matches the wave frequency. If the waves look frozen at half the true frequency, there are two waves between flashes, so always use the highest flash frequency that freezes them. At low frequencies you can instead count the waves passing a point in 10 s and divide by 10.
The scale factor. Put an object of known size, such as a credit card, in the tank. Measure its shadow on the paper. Scale factor = size on paper ÷ real size.
Measuring the wavelength. One wavelength is the distance from one bright line to the next. It is easier to measure from a still image: freeze the waves with the strobe, or take a photo. Measure across 10 wavelengths on the paper and divide by 10, which is more accurate than measuring one. Then divide by the scale factor to get the real wavelength in the tank.
Wave speed. Calculate v = fλ using the real wavelength. As a check, time one wave crossing the tank and use speed = distance ÷ time. The wave speed depends on the depth of the water, not on the frequency.
Safety. Water and electricity: keep the power supply away from the tank, and mop up spills.
About this simulation
This simulation recreates the GCSE required practical for measuring the frequency, wavelength and speed of water waves in a ripple tank. A vibrating dipper makes waves on the water, and a lamp above the tank projects the pattern onto paper underneath, where crests show as bright lines.
The frequency is measured with a stroboscope: when the flash frequency matches the wave frequency, the waves appear to stand still. At low frequencies the waves passing a point can be counted for 10 seconds instead. Because the pattern on the paper is magnified, a credit card in the tank is used to find the scale factor: its shadow measures 13.5 cm, compared with 5.4 cm in real life, so the scale factor is 2.5.
To find the wavelength, measure across 10 wavelengths on the paper, divide by 10, then divide by the scale factor. For example, 75 cm across 10 waves gives 7.5 cm on the paper, which is 3.0 cm in the tank. The wave speed is then v = fλ. As a check, time one wave crossing the tank and use speed = distance ÷ time.
