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# The Physics PHYA2 thread! 5th June 2013 Watch

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1. (Original post by Me123456789)
What do you think will come up tomorrow?
Me? I think an exam paper will come to me tomorrow. HAHA
2. (Original post by NabRoh)
Hey guys, if anyone could help me with this question I would be very very grateful. Cheers:

Diagram:

Question:

Info given: Refractive index of core is 1.47, RI of cladding is 1.45
Critical angle is 80.4 degrees

Thanks once again
Do you know what paper that is, so I can be sure of my answer?
3. (Original post by x-Sophie-x)
I don't see why, because 44 is the angle of incidence of the first boundary and not the second??
The N of the Oil is the same as the N of the Glass..

So the incident angle would be the same and the refractive angle you do 1.33sin50=1.47sin theta
and rearrange and you'll get 44 to 2 sig fig
4. (Original post by ccashman)
Do the waves of youngs double slit diffract as well as interfere ? Please explain
yeah, waves will be diffracted through each slit, and it is this spreading of the waves that allow them to 'overlap' each other, causing interference
5. Guyssss I need help with Question 4ciii on the Jan 2013 paper pleaseeeeeee
6. (Original post by NabRoh)
Hey guys, if anyone could help me with this question I would be very very grateful. Cheers:

Diagram:

Question:

Info given: Refractive index of core is 1.47, RI of cladding is 1.45
Critical angle is 80.4 degrees

Thanks once again
Well seeing as the light refracts ALONG the core cladding boundary you know that the angle from the normal is 90 degrees. The sin of 90 degrees is 1.

You then use snells law and re arrange

(Tried to help without giving you the full answer)
7. Does anyone know if there are any solution videos for the past papers?
8. (Original post by Qari)
The N of the Oil is the same as the N of the Glass..

So the incident angle would be the same and the refractive angle you do 1.33sin50=1.47sin theta
and rearrange and you'll get 44 to 2 sig fig
I get it now, thanks
9. So I am completely ready for the exam tomorrow except for a few things. I can't seem to get my head around the slit experiments, maxima/path difference and all that junk. Mechanics is really more my thing.

Does anyone have any good notes relating to diffraction gratings and the slit experiments. Thank you!
10. Is intensity constant for the DOUBLE SLIT diffraction or does it decrease with distance from the central maxima?
11. (Original post by Raimonduo)
Do you know what paper that is, so I can be sure of my answer?
June 11, how'd you do part d
12. Does anyone have the January 2013 PHYA2 paper? That would be so useful for tommorow
13. (Original post by StalkeR47)
Sorry Sophie. I am totally confused what you are trying to say. Do you know which exact question you need help with? Was the question on the video? If yes then at what time was it on?
Ah no. It wasn't in the video.

I just want to clarify, does TIR only happen when the ray moves from a more refractive substance to a less refractive substance? OR when the critical angle is larger the the incident ray?

Or does both have to be true?
14. (Original post by Cl28)
Is intensity constant for the DOUBLE SLIT diffraction or does it decrease with distance from the central maxima?
its constant but for single slit it decreases
15. (Original post by NabRoh)
Hey guys, if anyone could help me with this question I would be very very grateful. Cheers:

Diagram:

Question:

Info given: Refractive index of core is 1.47, RI of cladding is 1.45
Critical angle is 80.4 degrees

Thanks once again
Here's some help with the angles, different colour = different angle.

All I'm gonna say is: consider the critical angle and the way the light ray is reflecting along the boundary, as well as the application of Snells Law. Rest should be pretty simple.
16. (Original post by Mehul Sharma)
Does anyone have the January 2013 PHYA2 paper? That would be so useful for tommorow
Its on pages 27 and 31. If you so require, however, I can put them up one last time as my parting gift to this thread.
17. (Original post by x-Sophie-x)
Ah no. It wasn't in the video.

I just want to clarify, does TIR only happen when the ray moves from a more refractive substance to a less refractive substance? OR when the critical angle is larger the the incident ray?

Or does both have to be true?
TIR is when ray moves from more refractive to less refractive and the incident ray has to be greater than crictical angle
18. (Original post by StalkeR47)
Me? I think an exam paper will come to me tomorrow. HAHA
Really, you 'think'? I'm pretty sure an exam paper will definitely come...
19. Hey guys,
Do we actually need to know all the mathematics and proof behind single slit diffraction and diffraction grating? I can't get my head round it, and it seems quite a lot for AS.

By derivation, I mean this:
http://www.antonine-education.co.uk/...n_of_young.htm
20. (Original post by Raimonduo)
Here's some help with the angles, different colour = different angle.

All I'm gonna say is: consider the critical angle and they way the light ray is reflecting as well as the application of Snells Law. Rest should be pretty simple.
Oh I've been stupid. I used the wrong angle Thanks for the diagram and highlighting the angles

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