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The Physics PHYA2 thread! 5th June 2013

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Reply 1320
Do we need to know the proof of diffraction grating?
How do you draw the white light fringes with the spectrum of colours, do you just label the different colours?
Original post by Bixel
Do we need to know the proof of diffraction grating?


My teacher said that it was in the specification, so we should know it, but it hasn't come up before, and I don't know it (so hopefully it won't come up) :biggrin:
Original post by StalkeR47
Like this m8.


damn my eyes are going weird by looking at that!
Can someone help me with 7)b)ii) Why is the path difference the same as the wavelength?
Original post by mejdoub.wassim
Can someone help me with 7)b)ii) Why is the path difference the same as the wavelength?


Which paper?
Original post by BigBadJFly
Which paper?


Nvm, I understand it now haha.

Basically it was the Jan 13' one, the answers essentially asking for the path difference of the first order. I'm a bit rusty, since January to be fair!
Original post by masryboy94
haha no worries bro, its good we had this discussion, it actually made me think and be sure :biggrin: hope you get it now though :rolleyes: p.s. you look like a 120 UMS boy :wink: you know your info my man, its just abit of confusion we all get so dw :biggrin:


Oh thank you very much! You are also 120UMS boy. :smile: You will do really really well as I can already see. :smile:
Just out of query though, for 7)c) of Jan 13', what position is it referring to?
Reply 1329
hi, can anyone help me with question 6.(a) (ii) on the june 2012 paper. The mark scheme doesnt make sense to me?
Original post by mejdoub.wassim
Just out of query though, for 7)c) of Jan 13', what position is it referring to?


for the path difference one just count the wavelengths of each are youll see that its like 5 for one and 6 for the other
Original post by StalkeR47
Oh thank you very much! You are also 120UMS boy. :smile: You will do really really well as I can already see. :smile:


i really hope so man, would help put off so much pressure for my phya4 exam. btw are all you lot willing to talk about this exam after tomorrow or are you gnna chicken out (maybe like me) lool.
Reply 1332
what are the main definitions that might come up? CRAMMING
Original post by Qari
How do you work out critical angle? And what's the definition of critical angle?


SinC=n2/n1 where n1>n2

The critical angle is the incident angle at which the refracted ray will travel across the boundary of the substances. Any more than the critical angle and total internal reflection will occur.
Original post by mazzah
what are the main definitions that might come up? CRAMMING


someone posted a .pdf or a word .doc at the start of this thread with a list of definitions on :tongue:
Original post by lebron_23
You're right, sorry I should have made myself clearer. The maxima do indeed contain all of the colours from white light (only in the case where white light is used), but they just pick up a red tinge the further away they get from the central maxima. Apologies for any confusion caused there.

However, do remember that each maxima will only contain all the colours of the spectrum if white light is used. If, for example, a laser light is used (red light), then all of the maxima will take on a red hue/tinge/colour.


yeah, this only happens for white light

for a red laser or any other monochromatic light source, you will only get the colour of that wavelength
Reply 1336
Original post by Davelittle
someone posted a .pdf or a word .doc at the start of this thread with a list of definitions on :tongue:


ah right thanks!!!
Good luck to everyone doing this.

Hopefully it won't go as badly as I think it will, but I expect a lot of things to come up I don't understand. I need a miracle.
Original post by looloo4
hi, can anyone help me with question 6.(a) (ii) on the june 2012 paper. The mark scheme doesnt make sense to me?


as I understand it, any point within the same loop is basically the same in terms of their phase difference from another point on another loop

it does seem weird, because on that question, point X is clearly not at the max amplitude point (it is slightly to the right of it), so it doesn't seem to make sense that X and Y would be exactly out of phase by 180 degrees, because you'd think for this to be the case, point X would have be at the peak and point Y would have to be at the trough
Original post by StalkeR47
Like this m8.


whats that?

a single slit diffraction for white light?

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