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The Physics PHYA2 thread! 5th June 2013

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Original post by Me123456789
What do you think will come up tomorrow?


Me? I think an exam paper will come to me tomorrow. :smile: HAHA
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 :smile:


Do you know what paper that is, so I can be sure of my answer?
Reply 1162
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 :smile: and the refractive angle you do 1.33sin50=1.47sin theta
and rearrange and you'll get 44 to 2 sig fig :smile:
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
Guyssss I need help with Question 4ciii on the Jan 2013 paper pleaseeeeeee
Reply 1165
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 :smile:


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 :smile:

(Tried to help without giving you the full answer)
Does anyone know if there are any solution videos for the past papers?
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 :smile: and the refractive angle you do 1.33sin50=1.47sin theta
and rearrange and you'll get 44 to 2 sig fig :smile:


I get it now, thanks :smile:
Reply 1168
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!
Reply 1169
Is intensity constant for the DOUBLE SLIT diffraction or does it decrease with distance from the central maxima?
Reply 1170
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
Does anyone have the January 2013 PHYA2 paper? That would be so useful for tommorow
Original post by StalkeR47
Sorry Sophie. I am totally confused what you are trying to say.:confused: 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? :smile:


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?
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
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 :smile:


Here's some help with the angles, different colour = different angle.
helpwithangles.png
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.
(edited 10 years ago)
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.
Reply 1176
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 :smile:
Original post by StalkeR47
Me? I think an exam paper will come to me tomorrow. :smile: HAHA


Really, you 'think'? I'm pretty sure an exam paper will definitely come...:dontknow:
Reply 1178
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/Pages/Physics_2/Waves/WAV_07/derivation_of_young.htm
(edited 10 years ago)
Reply 1179
Original post by Raimonduo
Here's some help with the angles, different colour = different angle.
helpwithangles.png
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 :frown: Thanks for the diagram and highlighting the angles :smile:
(edited 10 years ago)

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