OCR Physics Unit 2 - G482 - (June Exams Preparation) Watch

motivatedshroom
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Thanks for replying ! Also is wave-particle duality: all particles (or waves?) interact with matter as photons and travel as waves


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rainbowsss
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(Original post by OllieGCSEs)
I potential divider is a circuit that uses the ratio of resistances in components to split the voltage up between them. When in series, two resistors share the voltage from the supply; the way it is divided between them is dependent on their resistances. E.g. if you have a dc supply of 6V, and resistors of 10 Ohms and 20 Ohms, then the respective p.d.s would be (10/30)*6 and (20/30)*6, i.e. 2V and 4V (which we can check using the fact that the total p.d.s equals the dc supply p.d. 2+4=6, success).

Does that make sense? If not, say so
Makes sense, thank you!
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m-s-96
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I would just like to add that I am ****** for tomorrow.


Thank you for your attention.
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Prince Obesity69
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(Original post by Frankster)
Qs 6b) of June 2012 paper!? Why is the graph in the answer basically reversed to the graph in the qs? http://www.ocr.org.uk/Images/131308-...nd-photons.pdf

Think of the 3 parts of the wave moving from left to right. point P stays in the same place like when you have a ball in the sea and the waves move over is but the ball stays in the same place.

that wave travels at 0.5ms-1 and the first part of the wave is 0.25m distance away from point P.
s=d/t → t =d/s so t=0.0.25/0.5 t=0.5 so the graph starts at 0.5 and reaches a maximum at 0.75 then you get negative displacement as the next part approaches then finally the last peak reaches P and it oscillates again.
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OllieGCSEs
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(Original post by cyiarik)
does anyone have the JAN 13 paper and markscheme? can you upload it or something please!!! i need it desperately!

thankyouuuu
Here you go
67 for an A i believe
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rainbowsss
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Another quickie, why does the resitance of an led decrease as voltage increaes? like for an IV charectertis graph

Thank you
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Prince Obesity69
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(Original post by OllieGCSEs)
Here you go
67 for an A i believe
thanks
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OllieGCSEs
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(Original post by rainbowsss)
Makes sense, thank you!
You're most welcome

(Original post by motivatedshroom)
Is wave-particle duality: all particles (or waves?) interact with matter as photons and travel as waves
Wave particle duality is simply the idea that waves can behave as particles (e.g. photoelectric effect) and that particles can behave as waves (e.g. electron diffraction)
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JamesJJT
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(Original post by Frankster)
Qs 6b) of June 2012 paper!? Why is the graph in the answer basically reversed to the graph in the qs? http://www.ocr.org.uk/Images/131308-...nd-photons.pdf
Sneaky little question that I fell for too.


The question asks you to draw the wave at P ;P
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_hail
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(Original post by OllieGCSEs)

I have a question too, which I'd greatly appreciate a response for: could someone please explain how spectral lines are evidence for the existence of energy levels in ionised atoms?

If you read my question and know the answer but cba to explain it, it might be worth realising that explaining the answer would develop your understanding But if you don't know the answer, quote me and bump the question!


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You get line emission spectra from the light emitted from a hot gas that is cooling down.
So all the excited electrons are moving back to their original discrete energy levels and in doing so emit photons of a wavelength corresponding to the energy difference they are moving through (E=hc/lambda). And each line on the spectrum corresponds to these specific wavelengths.
Hope that makes sense
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Layontheland
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(Original post by OllieGCSEs)
I would say 'polarising filter' as opposed to polaroid, because I think they sometimes reject it.

Do you know the question?
3C (ii) - June 2012
3C(iii) - June 2011

It's stated in the mark scheme.
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OllieGCSEs
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(Original post by _hail)
You get line emission spectra from the light emitted from a hot gas that is cooling down.
So all the excited electrons are moving back to their original discrete energy levels and in doing so emit photons of a wavelength corresponding to the energy difference they are moving through (E=hc/lambda). And each line on the spectrum corresponds to these specific wavelengths.
Hope that makes sense
I +repped you for responding , and yes, that does make sense could you also explain the absorption spectrum? I understand that one is produced when light is passed through a cool gas but why do the black lines appear?
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OllieGCSEs
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(Original post by Layontheland)
3C (ii) - June 2012
3C(iii) - June 2011

It's stated in the mark scheme.
I see - I think it refers to just stating the potential divider formula and working around that to explain the answer... I'm not going to worry about it though
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ReginaPhalange29
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Can someone explain what a negative temperature coefficient is?


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Rudokimbo
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Hi guys, just to say goodluck on your exam tomorrow, does anyone have any idea on what experiment we might be asked to describe??
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OllieGCSEs
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(Original post by ReginaPhalange29)
Can someone explain what a negative temperature coefficient is?
[/SIZE]
An NTC thermistor is a resistor whose resistance decreases when temperature increases. Don't worry about the NTC part, just know that a thermistor's resistance is affected by temperature in the opposite way to a regular resistor
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ReginaPhalange29
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(Original post by Rudokimbo)
Hi guys, just to say goodluck on your exam tomorrow, does anyone have any idea on what experiment we might be asked to describe??
Photoelectric effect maybe? Or polarising waves.


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ReginaPhalange29
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(Original post by OllieGCSEs)
An NTC thermistor is a resistor whose resistance decreases when temperature increases. Don't worry about the NTC part, just know that a thermistor's resistance is affected by temperature in the opposite way to a regular resistor
Thanks!


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Frankster
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Qs 6b) of June 2012 paper!? Why is the graph in the answer basically reversed to the graph in the qs? http://www.ocr.org.uk/Images/131308-...nd-photons.pdf
(Original post by Prince Obesity69)
Think of the 3 parts of the wave moving from left to right. point P stays in the same place like when you have a ball in the sea and the waves move over is but the ball stays in the same place.

that wave travels at 0.5ms-1 and the first part of the wave is 0.25m distance away from point P.
s=d/t → t =d/s so t=0.0.25/0.5 t=0.5 so the graph starts at 0.5 and reaches a maximum at 0.75 then you get negative displacement as the next part approaches then finally the last peak reaches P and it oscillates again.
Ohhhh so I guess you just had to spot that the front of the pulse is actually in the opposite direction and so that's why you get the reverse pattern?
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speedstar_mm
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What do we need to know off by heart that isn't in the formula book?
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