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Standing and Progressive Waves

This multiple choice is irratating me.

Which line in the table gives a correct difference between a progressive and stationary wave?

For each line RED gives the Progressive property and BLUE gives the stationary property

A All the Particles vibrate
Some of the particles do not vibrate
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B - None of the particles particles vibrate with the same Amplitude
All of the particles vibrate with the same amplitude
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C - All the particles vibrate in phase phase with each other
None of the particles vibrate in phase with each other
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D - Some of the particles vibrate in phase with each other All of the particles vibrate in phase with eachother
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This is verbatim from the Jan 05 PYa4 paper - the markscheme of which I have here - and the paper - I went for A - this is apparently incorrect - can someone please enlighten me :smile:

Thank you

Reply 1

Morbo

A - I'd say this was the answer too. In a travellling wave, every particle experiences varying displacement as the wave travels through (so vibrates), whereas in a stationary wave there are nodes (zero displacement) where some particles do not vibrate.
B - Not true: for a stationary wave, the particles all have different amplitudes.
C - Not true: for a stationary wave, some of the particles vibrate in phase with each other.
D - Not true: for a stationary wave, some of the particle vibrate in anti-phase with each other.

EDIT: Good lord, yes - I was thinking of the fundamental, where they are all in phase, which is not true generally. All changed now. What on earth does the markscheme argue??

Reply 2

F1 fanatic

I agree, both A and D are as far as I see it correct :confused:

.

Edit: Wait, no, D is wrong also since half the particles are in phase and half in antiphase for a standing wave. Therefore it has to be A, whatever the mark scheme may say.