Exam-style question
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Why can longitudinal waves not be polarised?.
- A.They do not have a defined direction of travel
- B.They oscillate parallel to the direction of travel
- C.They have a constant frequency
- D.They travel slower than transverse waves
Model answer
What a good answer should say
- They oscillate parallel to the direction of travel
Explanation
Why this works
The cause of the inability to polarise longitudinal waves is that they oscillate parallel to the direction of travel. This mechanism means that there is no single plane of vibration to restrict, leading to the effect that longitudinal waves cannot be polarised.
The consequence is that this characteristic differentiates them from transverse waves, which can be polarised.
Common mistake
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