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# Edexcel Physics Unit 2 "Physics at work" June 2013 Watch

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1. (Original post by Gunner121)
Doppler effect ??? Someone please explain

learn that definition.
2. For june 2011 question 11 I think it is (the one where you have to work out the resistance) for the last one I thought the total of the two resistors in series is 2R and then so 1/2R + 1/R = 3/2R but what's wrong, what am I doing wrong?
3. (Original post by ArcRaman)
BBB - blue bends better
RBR - red bends rotten.

Therefore you can see that if blue and red light travel in the same media, other than vacuum, blue light will always have to experience a greater index of refraction.
So shorter wavelengths refract more?

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4. (Original post by Tomupcraft)

learn that definition.
That was nice !
5. Jan 11 q11c) - how are you supposed to know to where to mark the compressions on Z? I feel like I'm missing something really obvious but I just can't see it!
6. Jan 11 can somebody please explain qu. 19?
7. (Original post by Gunner121)
Doppler effect ??? Someone please explain
Use brightstorm2 channel in YouTube it is excellent!
8. (Original post by ambbs)
Jan 11 q11c) - how are you supposed to know to where to mark the compressions on Z? I feel like I'm missing something really obvious but I just can't see it!
One time period is between adjacent compressions. If the wave had traveled T the positions would basically look the same, the particles would have just moved up the line. However as 3/4T has passed then the compressions must be 3/4 along the line between two compressions.

If that does not make sense I will try to explain further.
9. (Original post by Tomupcraft)
One time period is between adjacent compressions. If the wave had traveled T the positions would basically look the same, the particles would have just moved up the line. However as 3/4T has passed then the compressions must be 3/4 along the line between two compressions.

If that does not make sense I will try to explain further.
Ah okay so if 1/2T had passed, the compressions would be halfway along the line between two compressions, i.e., at a rarefaction? Thanks!
10. (Original post by ambbs)
Ah okay so if 1/2T had passed, the compressions would be halfway along the line between two compressions, i.e., at a rarefaction? Thanks!
Yes, that is correct.
11. How to solve this question? The answer is 'D'. Anyone please.
12. (Original post by Tomupcraft)
Yes, that is correct.
Could you explain, so the larger the wavelength the more it refracts and bends away from the normal in a denser medium ?

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13. (Original post by AT95)
I have explained this on the previous page
14. (Original post by alygirl)
Jan 11 can somebody please explain qu. 19?
I hope you get it

15. How do you label something out of phase? I'm thinking of question 12 Jan 09
16. (Original post by Branny101)
Could you explain, so the larger the wavelength the more it refracts and bends away from the normal in a denser medium ?

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No, The smaller the wavelength, hence greater the frequency the more the wave refracts.
therefore if we take red and blue light, blue light will refract greater towards the normal than red light.

Diffraction is the opposite, the greater the wavelength the greater the diffraction.
17. (Original post by alygirl)
Jan 11 can somebody please explain qu. 19?
Here is the second one :

18. (Original post by alygirl)
How do you label something out of phase? I'm thinking of question 12 Jan 09
Do you mean out of phase or 180 degrees out of phase? out of phase can be anything that is not in phase with a point, wheres a point in anti phase must be 180 degrees out of phase.
19. (Original post by krisshP)
Use brightstorm2 channel in YouTube it is excellent!
Okay
20. (Original post by Gunner121)
Okay
(Original post by Tomupcraft)
Do you mean out of phase or 180 degrees out of phase? out of phase can be anything that is not in phase with a point, wheres a point in anti phase must be 180 degrees out of phase.
(Original post by Branny101)
Could you explain, so the larger the wavelength the more it refracts and bends away from the normal in a denser medium ?

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