# AS Edexcel Physics: Superposition of waves

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#1
Can anyone give me a link with a good summarisation of superposition of waves? None of the edexcel books give a satisfying explanation (in layman terms); (for someone who has never studied this particular topic)..

Thanks
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8 years ago
#2
(Original post by xXxiKillxXx)
Can anyone give me a link with a good summarisation of superposition of waves? None of the edexcel books give a satisfying explanation (in layman terms); (for someone who has never studied this particular topic)..

Thanks
When two waves travelling in opposite directions overlap each other. If they have the same amplitude and frequency (and phase difference I think) it will result in a single wave with a larger amplitude than the original amplitude. If the waves have different amplitude, frequency (and phase difference I think) they will interrupt each other (destructive interference) and cancel each other out. Hope this helps, trying remember what I can from last year
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#3
(Original post by TLK)
When two waves travelling in opposite directions overlap each other. If they have the same amplitude and frequency (and phase difference I think) it will result in a single wave with a larger amplitude than the original amplitude. If the waves have different amplitude, frequency (and phase difference I think) they will interrupt each other (destructive interference) and cancel each other out. Hope this helps, trying remember what I can from last year
Thanks I understand that part! But in my book there is something about path difference and I have no clue what its about..
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8 years ago
#4
http://www.physicsclassroom.com/class/light/u12l3b.cfm

Path difference or PD is the difference in distance traveled by the two waves from their respective sources to a given point on the pattern.
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1 year ago
#5
This is very wrong. The waves don´t have to be travelling in opposite direction in order for superposition to take place. That is only necessary for a standing wave to form. Also superposition can occur for two or more waves. For the superposition to produce a fixed pattern the waves must be coherent ( same frequency, wavelength and waveform and a constant phase relationship) and have a similar amplitude at the point of interference. An example of this fixed patterns are formed when two waves which are in phase (i.e 2pi*n phase difference or what is the same: n*lambda path difference) and interfere contructively or two waves in antiphase (i.e. (2*n + 1)pi or what is the same: (n 1/2)lambda path difference) which interfere destructively and completely cancel out. Otherwise, if the waves are not coherent, superposition is simply when two or more waves meet at the same point at the same time and overlap giving a net displacement or amplitude equal to the sum of the displacements/amplitudes that would have been produced by the individual waves separately.
Last edited by pga_01; 1 year ago
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1 year ago
#6
(Original post by pga_01)
This is very wrong. The waves don´t have to be travelling in opposite direction in order for superposition to take place. That is only necessary for a standing wave to form. Also superposition can occur for two or more waves. For the superposition to produce a fixed pattern the waves must be coherent ( same frequency, wavelength and waveform and a constant phase relationship) and have a similar amplitude at the point of interference. An example of this fixed patterns are formed when two waves which are in phase (i.e 2pi*n phase difference or what is the same: n*lambda path difference) and interfere contructively or two waves in antiphase (i.e. (2*n 1)pi or what is the same: (n 1/2)lambda path difference) which interfere destructively and completely cancel out. Otherwise, if the waves are not coherent, superposition is simply when two or more waves meet at the same point at the same time and overlap giving a net displacement or amplitude equal to the sum of the displacements/amplitudes that would have been produced by the individual waves separately.
This forum was created in the 17th century. Their physics wasn't as advanced as ours.
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1 year ago
#7
gotta get things right

(Original post by FatoraPator)
This forum was created in the 17th century. Their physics wasn't as advanced as ours.
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1 year ago
#8
(Original post by pga_01)
gotta get things right
They have to be coherent to superposition right?
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1 year ago
#9
(Original post by FatoraPator)
They have to be coherent to superposition right?
Nah - you always get superposition when waves meet... but superposition only results in a standing wave under very specific conditions as stated above.

commonly you get a standing wave when you reflect a wave so that it's going back into the same space in the reverse direction... but you could also do it with e.g. loudspeakers at different positions connected to the same signal generator.
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1 year ago
#10
I know this thread is very old, but I have some resources to help if anyone still needs help with superposition of waves.

Here is a link to a document I prepared which covers all the superposition of waves content in the OCR A specification, but I'm fairly sure the specification for Edexcel will be very similar so this document should still be fine.

The diagrams aren't included in the document since I didn't know how to insert images into LaTeX at the time I wrote it but you can easily refer to a textbook or print and copy the diagrams in.

The notes in the document cover and explain path difference and a number of other concepts.

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1 year ago
#11
(Original post by xXxiKillxXx)
Can anyone give me a link with a good summarisation of superposition of waves? None of the edexcel books give a satisfying explanation (in layman terms); (for someone who has never studied this particular topic)..

Thanks
https://www.antonine-education.co.uk...el_1.htm#Waves

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