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A level Physics waves

Can someone please please please help with this question. The answer is 0.1m..
(edited 9 months ago)
Show the whole question?
Reply 2
Here the first part but I don’t see how it would help
Reply 3
The waves interfere when they reach Y and the sound at Y is quietest when the waves cancel each other out which is when destructive interference occurs, for this to occur the path difference between the waves must be in the form (n+0.5) x wavelength where n is an integer. So the minimum path difference is when n=0 and therefore the path difference is 0.5 x wavelength. You can find the wavelength using v=f x wavelength with the values they've given, but when you shift the tube by 1 meter, for example, this will increase the distance travelled by the wave by 2 meters because you are increasing the length of both horizontal sections by 1 meter. So once you find the wavelength you should half it to get the necessary path difference and then half it again to get the distance you have to extend the tube.

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