OCR · GCSE · Physics
Course version: J249 · Version from Sept 2018
Making observations of waves in fluids and solids to identify the…
Full specification wording
Measuring waves: Making observations of waves in fluids and solids to identify the suitability of apparatus to measure speed/frequency/wavelength.
This practical activity asks you to watch waves travelling through a fluid (such as water in a ripple tank) and through a solid (such as a stretched string or a metal rod), then judge which…
Checked against the OCR J249 specification (opens in a new tab) on .
- Point 2 of 2
- 4 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
This practical activity asks you to watch waves travelling through a fluid (such as water in a ripple tank) and through a solid (such as a stretched string or a metal rod), then judge which apparatus suits measuring speed, frequency or wavelength. You generate or observe the wave, note what you can actually see or detect, and match the instrument to the quantity: a signal generator and vibration generator suit a string, a stroboscope or slow-motion camera helps freeze a ripple pattern, a metre rule measures wavelength, and a timer with a known number of oscillations gives frequency. Suitability means the apparatus produces a clear, repeatable reading at the scale of the wave, not merely that it is available.
What earns the marks
- Identifies that a ripple tank with a lamp projects a visible wave pattern suitable for measuring wavelength in a fluid.
- Selects a vibration generator and signal generator as suitable apparatus for producing waves on a stretched string at a set frequency.
- Explains that a stroboscope or slow-motion recording makes a fast-moving wave pattern observable so wavelength can be measured.
- Matches each measuring instrument to the quantity it measures, such as a metre rule for wavelength and a timer for frequency.
- Judges suitability by whether the apparatus gives a clear, repeatable reading at the scale of the observed wave.
Common mistakes and how to put them right
Chooses apparatus without linking it to the quantity being measured.
Put it right: State which instrument measures speed, frequency or wavelength and why.
Assumes any available instrument is suitable.
Put it right: Check that it gives a clear, repeatable reading at the wave's scale.
Confuses frequency with wavelength when selecting apparatus.
Put it right: Keep the two quantities and their instruments distinct.
Exam tips
- Name the wave medium first (fluid or solid), then choose apparatus that works for that medium.
- Link every instrument you pick to the specific quantity it measures.
- Justify suitability by referring to clarity and repeatability of the observation, not just availability.
Try the lesson
The start of the Measuring waves: Making observations of waves in fluids and solids to identify the suitability of apparatus to measure speed/frequency/wavelength. lesson, made from checked teaching notes for this specification point.
Have a go first
A student wants to measure the wavelength of ripples on the surface of water in a ripple tank. Which piece of apparatus is most suitable for this measurement?
Listen
This practical activity asks you to watch waves travelling through a fluid (such as water in a ripple tank) and through a solid (such as a stretched string or a metal rod), then judge which apparatus suits measuring speed, frequency or wavelength. You generate or observe the wave, note what you can actually see or detect, and match the instrument to the quantity: a signal generator and vibration generator suit a string, a stroboscope or slow-motion camera helps freeze a ripple pattern, a metre rule measures wavelength, and a timer with a known number of oscillations gives frequency. Suitability means the apparatus produces a clear, repeatable reading at the scale of the wave, not merely that it is available. A strong answer earns marks for these points. Identifies that a ripple tank with a lamp projects a visible wave pattern suitable for measuring wavelength in a fluid. Selects a vibration generator and signal generator as suitable apparatus for producing waves on a stretched string at a set frequency. Explains that a stroboscope or slow-motion recording makes a fast-moving wave pattern observable so wavelength can be measured. Matches each measuring instrument to the quantity it measures, such as a metre rule for wavelength and a timer for frequency. Exam tip: Name the wave medium first (fluid or solid), then choose apparatus that works for that medium.
Key words
Say what each word means before you turn the card.
Observing waves in fluids
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Observing waves in solids
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Selecting apparatus for speed, frequency and wavelength
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Judging suitability of measurements
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See every definition
- Observing waves in fluids
- Watching waves travelling through a fluid, such as water in a ripple tank, and noting what can actually be seen or detected.
- Observing waves in solids
- Watching waves travelling through a solid, such as a stretched string or a metal rod, and noting what can actually be seen or detected.
- Selecting apparatus for speed, frequency and wavelength
- Matching the instrument to the quantity, such as a metre rule for wavelength and a timer for frequency.
- Judging suitability of measurements
- Deciding whether apparatus gives a clear, repeatable reading at the scale of the observed wave, not merely that it is available.
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