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June 2011 question 7a g482 ocr physics

what does this mean in the brackets at the end ?in the mark scheme:

oscillations/vibrations in one direction only/confined to single plane (containing the direction of propagation)
Reply 1
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emsablah
5
Original post by runny4
what does this mean in the brackets at the end ?in the mark scheme:

oscillations/vibrations in one direction only/confined to single plane (containing the direction of propagation)



The direction of propagation means the direction in which the wave is travelling/ energy is being transferred. If you say oscillations in only one plane, that plane could be perpendicular to the direction of propagation, in which case it could be any direction. so you have to say containing the direction of propagation. It's quite hard to explain without visuals. I think if you get this question it's easier just to say oscillations in only one direction. That way there's no ambiguity.
Reply 2
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runny4
OP
6
Original post by emsablah
The direction of propagation means the direction in which the wave is travelling/ energy is being transferred. If you say oscillations in only one plane, that plane could be perpendicular to the direction of propagation, in which case it could be any direction. so you have to say containing the direction of propagation. It's quite hard to explain without visuals. I think if you get this question it's easier just to say oscillations in only one direction. That way there's no ambiguity.


but isn't the plane of oscillations always perpendicular to energy transfer for a transvere polarised wave?
Reply 3
Avatar for runny4
runny4
OP
6
Original post by emsablah
The direction of propagation means the direction in which the wave is travelling/ energy is being transferred. If you say oscillations in only one plane, that plane could be perpendicular to the direction of propagation, in which case it could be any direction. so you have to say containing the direction of propagation. It's quite hard to explain without visuals. I think if you get this question it's easier just to say oscillations in only one direction. That way there's no ambiguity.


also do you want me to private message all of the question papers and mark schemes if you can't find them?
Reply 4
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emsablah
5
Original post by runny4
but isn't the plane of oscillations always perpendicular to energy transfer for a transvere polarised wave?


Exactly. so the oscillations are always in one plane anyway - the plane perpendicular to energy transfer - even if it's unpolarised. so saying 'only in one plane' applies to all transverse waves, not just polarised ones, so this does not answer the question!
Reply 5
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runny4
OP
6
Original post by emsablah
Exactly. so the oscillations are always in one plane anyway - the plane perpendicular to energy transfer - even if it's unpolarised. so saying 'only in one plane' applies to all transverse waves, not just polarised ones, so this does not answer the question!

yeah i get that the oscillations/vibrations are in one direction only/confined to single plane
but they don't(contain the direction of propagation)they are perpendicular to it!
Reply 6
Avatar for emsablah
emsablah
5
Original post by runny4
yeah i get that the oscillations/vibrations are in one direction only/confined to single plane
but they don't(contain the direction of propagation)they are perpendicular to it!


don't confuse the words 'plane' and 'direction'. 'Plane' is a two-dimensional thing, whereas 'direction' is only in one dimension. the oscillations can be perpendicular to the direction of propagation, but still be in the same plane. In this context it is much better to just use the word 'direction' - you will definitely get the mark for that.
Reply 7
Avatar for runny4
runny4
OP
6
Original post by emsablah
don't confuse the words 'plane' and 'direction'. 'Plane' is a two-dimensional thing, whereas 'direction' is only in one dimension. the oscillations can be perpendicular to the direction of propagation, but still be in the same plane. In this context it is much better to just use the word 'direction' - you will definitely get the mark for that.


well the mark scheme says:
reference to a transverse wave or to vibrations in plane normal to the direction of (energy) propagation. oscillations/vibrations in one direction only/confined to single plane (containing the direction of propagation)

but i think where they said
vibrations in plane normal to the direction of (energy) propagation
it is contradicted by
oscillations/vibrations in one direction only (containing the direction of propagation)

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