New
New
Year 10
Edexcel
Higher

# Measuring waves in a ripple tank

I can accurately measure the wavelength, frequency and wave speed of water waves in a ripple tank.

New
New
Year 10
Edexcel
Higher

# Measuring waves in a ripple tank

I can accurately measure the wavelength, frequency and wave speed of water waves in a ripple tank.

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## Lesson details

### Key learning points

1. Frequency of a wave can be measured indirectly from its speed and wavelength.
2. Wavelength of a wave can be measured by using a freeze frame of a wave moving along the length of a ruler.
3. It is more accurate to measure the length of, e.g. ten waves and dividing by ten, than measuring one wavelength.
4. Speed of a wave can be measured by recording the wave moving along a ruler with a timer in the frame.
5. Accurate distance and time are measured by freezing the film, played back in slow motion, to track one wave crest.

### Common misconception

In the equation for the speed of a wave, v = f x λ, speed is dependent on frequency and/or wavelength.

Emphasise that the speed of a wave depends only on the wave medium and not on frequency or wavelength.

### Keywords

• Ripple tank - A vibrating beam in a ripple tank creates water waves in a clear bottomed container that makes the waves easier to observe.

• Slow motion - A film played back in slow motion shows everything happening slowly, including the speed of a timer shown in the film.

• Wave equation - The wave equation is: wave speed = frequency × wavelength, v = f × λ.

• Uncertainty - The uncertainty in a measurement can be expressed as the range of values within which the true value must lie.

• Significant figures - The number of significant figures of a measurement depends on how accurately the measurement is made.

The investigation could alternatively be carried out as a demonstration, perhaps using a visualiser.
Teacher tip

### Content guidance

• Equipment requiring safe usage.
• Contains flashing images.

### Licence

This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

## Starter quiz

### 6 Questions

Q1.
In which of the following directions does the water move in a water wave?
forwards and backwards
side to side
Q2.
Which of the following accurately describes a water wave?
longitudinal
mechanical
Q3.
In which of the following directions should a wooden beam move in a trough of water to create water waves?
side to side
forwards and backwards
Q4.
Which of the following type of results do repeat measurements help to identify?
accurate results
average results
Q5.
A result is if it is very different from other measurements of the same variable.
Correct Answer: anomalous, wrong, a mistake
Q6.
Which of the following measurements are needed to find the frequency of a water wave?
distance and time
wavelength and time

## Exit quiz

### 6 Questions

Q1.
Which of the following pieces of equipment can be used to observe the behaviour of water waves in the classroom?
water tank
glass trough
Q2.
The frequency of a water wave equals the number of waves second.
Correct Answer: per, each, every, in one
Q3.
Which of the following happens if the motor controlling the wooden beam on a ripple tank is made to spin faster?
Correct answer: The frequency of the waves increases.
The speed of the wave increases.
The wavelength of the wave increases.
Q4.
The wave speed of a water wave equals the multiplied by the wavelength.
Q5.
The frequency of a water wave equals the wave speed divided by the ...