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Unit 2 - Stationary Waves Question

Hi I was doing my first past paper and I got stuck on this question and no matter how much I try i cant seem to understand how they arrive at the answer.

The question is 4bi on
http://store.aqa.org.uk/qual/gce/pdf/AQA-PHYA2-W-QP-JAN10.PDF

And the markscheme is here
http://store.aqa.org.uk/qual/gce/pdf/AQA-PHYA2-W-MS-JAN10.PDF

How am I supposed to know how to draw this. Surely I can draw it however I want as long I put a node where they have told me :confused:

Thanks

(edited 11 years ago)

Reply 1

joostan

Original post by user1-4

Thanks

There must be nodes at places where the string is in a fixed point in space - i.e. the bridges. The wavelength is assumed to be constant, so the nodes must be evenly spaced.

Reply 2

user1-4

Ok thank you.
Does the wave then have 5 nodes and 4 antinodes?

Reply 3

x0diak

Original post by user1-4

Ok thank you.
Does the wave then have 5 nodes and 4 antinodes?

Yes it does.

Are you also going to be sitting this exam in the summer?

I am finding diffraction, diffraction gratings, springs and moments the most difficult topics for me to understand.

Are you able to give me any tips/practice exercises that helped you understand them? :smile:

Reply 4

user1-4

yes I am sitting it in the summer. For diffraction and diffraction gratings all you really need to know is what the letter in the equation stand for. Once you know that when they ask you a worded question just put some easy numbers in and see what result you get.

e.g. If wavelength increases what happens to fringe spacing.
Put every number as 1 and work out fringe spacing. then increase wavelength to 2 and see what happens to fringe spacing.

I also find springs and moments hard. Aswell as stationary waves :frown:

Any tips?

Reply 5

x0diak

Ahh okay I'll practice my diffraction grating skills :colone:

My main help for stationary waves was: http://www.s-cool.co.uk/a-level/physics/progressive-waves/revise-it/standing-waves

Moments seems so easy in terms of it's equation, but I never know where to take moments from :frown:

Reply 6

user1-4