# Many students think that the amplitude (like wavelength) is in some way proportional to frequency and speed

Light, Sound and Waves

Misconception

### Diagnostic Resources

The following worksheets may help to identify whether students hold this particular misconception.

• #### Taking care with technical terms - amplitude (14-16)

Ref - SPT Ra01TL05

Being precise when talking about amplitude

Wrong Track:The amplitude of a sound wave is how big it is.

Right Lines:The amplitude of a sound wave is the difference in density at the points of zero and maximum displacement of any point on the wave.

View Resource
• #### "Estimating wavelength, frequency, and velocity of ripples (11-16)

Ref - Practical Physics; Waves; Measuring waves in a ripple tank;

It should be possible to calculate whether frequency x wavelength is near to the measured value for the velocity.  By elimination, it can be shown that amplitude does not influence frequency.

View Resource
• #### "Episode 311: Speed, frequency and wavelength (16-19)

Ref - TAP; Teaching vibrations and waves;

This episode considers how these three quantities are linked by the wave equation v = f ×  λ , measuring f using an oscilloscope, and measuring the velocity of sound in free air.  Again it can be shown there is no link between frequency and amplitude.

View Resource

## References

The following studies have documented this misconception:

• Pejuan, A., Bohigas, X., Jaen, X. and Periago, C. () Misconceptions about sound among engineering students, Journal of Science Education and Technology, 21,

669-685.