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The Physics PHYA2 thread! 5th June 2013 watch

• View Poll Results: What mark do you think you got out of 70?
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6
2.99%
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12
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41-50
29
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80
39.80%
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1. (Original post by _JasmineMistry)
When you do the double slit do you always have to include the first single slit?
The first slit polarises the light and makes it coherent. I think a laser has the same effect so you only use the first slit of you're using a lamp;it's not necessary with a laser light. I'm pretty sure that's how it works...

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3. (Original post by _JasmineMistry)
When you do the double slit do you always have to include the first single slit?
Spoiler:
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Only if the incident light is not coherent.
If candle light etc, single slit is used to produce two coherent light sources.

If incident light is a monochromatic laser than you do not have to.
That is my understanding.

edit: That is what I typed first then I read that "light acts as random bursts so it would be impossible to align the lights without first diffracting through a single slit"

To be on the safe side use a single slit then a double.
4. (Original post by BayHarborButcher)
I reckon somethng like that might actually come up you know. But how much would it be worth? So you would say that one transfers energy the other one doesnt? One travels whilst one is stationary? One is the result of superposition? And so on...
Same, I think it might come up. It would be 3-4 marks I think. They both travel but stationary wave travel in opposite direction.
(Original post by Felix Ivers)
A progressive wave travels in space whereas a stationary wave is fixed at 2 ends causing it to reflect and produce 2 interfering waves with a fixed number of nodes and antipodes dependant on frequency?

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Yes. That give you 2-3 marks.
5. Jan 2012 how did they get 65 degrees for 4biii
stationary transfer no energy and are formed by two waves of similar amplitude, frequency and wavelength being superposed, e.g from being reflected back onto each other

progressive waves transfer energy - longitudinal energy is transferred parallel to direction of travel of wave

transverse - energy transferred perpendicular to the direction of travel of wave

how many marks was it?
It was 4 marks. 2 for stationary wave and 2 for progressive wave. And, that all is correct!
7. 2pi d / wavelength is how you work out phase difference right!? I'm stressing now....
8. (Original post by StalkeR47)
It was 4 marks. 2 for stationary wave and 2 for progressive wave. And, that all is correct!
phew, i cant wait until the exam is over tomorrow! Still have all my A2 exams to sit yet! astrophysics, unit 5 chem and unit 5 biology, cant wait for university, i just hope I meet my offer!!!
9. (Original post by NabRoh)
2pi d / wavelength is how you work out phase difference right!? I'm stressing now....
10. (Original post by Micheal123456)
Jan 2012 how did they get 65 degrees for 4biii
From what I can remember on the far right that beam of light is undergoing total internal reflection, so the angle within this triangle must also be 85 degrees. angles within a triangle must equal 180 degrees, I'm sure you can figure it out from there
11. (Original post by NabRoh)
2pi d / wavelength is how you work out phase difference right!? I'm stressing now....
phew, i cant wait until the exam is over tomorrow! Still have all my A2 exams to sit yet! astrophysics, unit 5 chem and unit 5 biology, cant wait for university, i just hope I meet my offer!!!
I hope that you will meet the offer and Best of luck!
13. (Original post by StalkeR47)
Cheers!
The equivalent is 360 d / wavelength in degrees right?
14. so nervous for this exam...so harddd
15. (Original post by StalkeR47)
I hope that you will meet the offer and Best of luck!
thanks mate best of luck to you aswell, gonna read the revision notes i made one last time and go to bed

good luck all
16. how does diffraction grating work?
17. Is the 'd' in dSin© = n lambda the distance between slits in the grating or distance between zero and first order beam?

Apologies for the makeshift theta

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18. (Original post by NabRoh)
Cheers!
The equivalent is 360 d / wavelength in degrees right?
Yes! But, use 2 pi so that you get answer in pi rad.
19. (Original post by Felix Ivers)
Is the 'd' in dSin© = n lambda the distance between slits in the grating or distance between zero and first order beam?

Apologies for the makeshift theta

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Distance between slits. They won't expect you to use anything else (like distance between orders)
20. (Original post by Felix Ivers)
Is the 'd' in dSin© = n lambda the distance between slits in the grating or distance between zero and first order beam?

Apologies for the makeshift theta

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No m8. d is the slit spacing. and big D for w=lambda D/s is the distance between the screen and the slits.

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