Question Constellation Sign up for free AQA · GCSE · Physics · Higher
Frequency and Wavelength Investigation
A teacher demonstrated how the frequency of a wave on a string affects the wavelength of the wave.
Figure 1 shows the equipment used.
The frequency of the signal generator is adjusted so that the wave shown in Figure 1 is seen.
At this frequency the string vibrates between the two positions shown in Figure 1.
Describe a method the teacher could use to investigate how the frequency of the wave affects the wavelength.
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Marking points
- 1 Gives a method capable of producing a valid frequency-wavelength outcome, with key steps in a logical sequence.
- 2 Explains how frequency is varied and a steady/stationary wave pattern is obtained.
- 3 Explains how wavelength is measured using the metre rule, moving the bridge as needed.
- 4 Controls the number of masses and repeats for different frequencies or stationary-wave patterns.
Full-mark answer
Keep the number of masses the same so the tension stays constant. Set a frequency on the signal generator and move the wooden bridge until a steady stationary wave is produced. Measure the wavelength with the metre rule. Repeat for a range of frequencies, obtaining a stationary wave and measuring its wavelength each time.
Why this answer loses marks
Change the frequency and record the wavelength.
This does not say how to obtain a stationary wave, measure wavelength, keep the tension constant, or repeat across frequencies, so it is not a valid sequenced method.