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

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#421

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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#422

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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

**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

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#423

I would just like to add that I am ****** for tomorrow.

Thank you for your attention.

Thank you for your attention.

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#424

(Original post by

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

**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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#425

(Original post by

does anyone have the JAN 13 paper and markscheme? can you upload it or something please!!! i need it desperately!

thankyouuuu

**cyiarik**)does anyone have the JAN 13 paper and markscheme? can you upload it or something please!!! i need it desperately!

thankyouuuu

67 for an A i believe

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#426

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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#428

(Original post by

Makes sense, thank you!

**rainbowsss**)Makes sense, thank you!

(Original post by

Is wave-particle duality: all particles (or waves?) interact with matter as photons and travel as waves

**motivatedshroom**)Is wave-particle duality: all particles (or waves?) interact with matter as photons and travel as waves

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#429

**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

The question asks you to draw the wave at

**P**;P

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#430

(Original post by

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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**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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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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#431

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I would say 'polarising filter' as opposed to polaroid, because I think they sometimes reject it.

Do you know the question?

**OllieGCSEs**)I would say 'polarising filter' as opposed to polaroid, because I think they sometimes reject it.

Do you know the question?

3C(iii) - June 2011

It's stated in the mark scheme.

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#432

(Original post by

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

**_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

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#433

(Original post by

3C (ii) - June 2012

3C(iii) - June 2011

It's stated in the mark scheme.

**Layontheland**)3C (ii) - June 2012

3C(iii) - June 2011

It's stated in the mark scheme.

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#434

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#435

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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#436

(Original post by

Can someone explain what a negative temperature coefficient is?

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**ReginaPhalange29**)Can someone explain what a negative temperature coefficient is?

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#437

(Original post by

Hi guys, just to say goodluck on your exam tomorrow, does anyone have any idea on what experiment we might be asked to describe??

**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??

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#438

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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

**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

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#439

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

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?

(Original post by

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.

**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.

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