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

Joseph-
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has anybody made a long answer / experiment pdf showing how to answer them?
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blackstarz
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(Original post by Dizzie31)
On the questions that increase the intensity, such as in the june 2009 paper q4b(ii)
Do you have to work out the amplitude? if so how
on the mark scheme it just says - sine wave of same frequency with any increased amplitude
I believe the intensity was double, since I=A^2 if the intensity increases by two then the amplitude must have increased by a factor of route 2.
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Dizzie31
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(Original post by blackstarz)
I believe the intensity was double, since I=A^2 if the intensity increases by two then the amplitude must have increased by a factor of route 2.
ahh thanks ;0
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JamesWire
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Just a couple of questions. On the past paper how can you prove the resistance of the setup is 3.2k ohms?

Secondly, with the textbook circuit I understand how they have calculated current for the resistors in series, but they then presume the resistors in parallel must both have a pd of 4v due to Kirchhoff's second law (i.e. 4v is the pd remaining).

With parallel circuits what are the laws for pd in branches, particularly when there is more than one component in a branch?

Thanks.
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DanKeitley
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Can anyone confirm whether this is an acceptable circuit for determining the I-V characteristic of any component? In the Jan 13 mark scheme it says: 'variable power supply or fixed supply + potential divider, ammeter in series with and voltmeter in parallel with lamp' so I assume it would be ok...?

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FaisalTreShah
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(Original post by Layontheland)
I found another post regarding this. They said:

it's a battery we're talking about here.
The positive terminal of the battery is a source of positive charge.
The chemical reaction in the electrolyte moves positive charges towards the positive terminal. That's what makes it positive.


Damn... well, better to learn things late than never I suppose! Thank you for the correction.
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JamesWire
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(Original post by DanKeitley)
Can anyone confirm whether this is an acceptable circuit for determining the I-V characteristic of any component? In the Jan 13 mark scheme it says: 'variable power supply or fixed supply + potential divider, ammeter in series with and voltmeter in parallel with lamp' so I assume it would be ok...?

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This circuit is generally better. You can easily vary pd across component from 0 to maximum and it gives a wider range of resistance variations.
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DanKeitley
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(Original post by JamesWire)
This circuit is generally better. You can easily vary pd across component from 0 to maximum and it gives a wider range of resistance variations.
Ok thanks. How is the potential difference varied though? do you change the resistance of the resistor?
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Layontheland
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(Original post by FaisalTreShah)
Damn... well, better to learn things late than never I suppose! Thank you for the correction.
No problem
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FaisalTreShah
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(Original post by viyas07)
can somebody please please explain things we neeed to know about absorption spectrum, emission spectrum,line spectrum, band spectrum and everything or anything thats related to them and how to work out anything related to spectrum questions!!!!!

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Absorption Spectrum: Dark lines, bright background.
Emission Spectrum: Bright lines, dark background.
Spectrum - Where ALL of the wavelengths/frequencies are present (in the radiation).

As photons are absorbed, they move UP the "energy level ladder".
As photons are emitted, they move DOWN the "energy level ladder".

That's all I've got to offer so far, hope this helps.

EDIT: Emission Line Spectrum are from hot gasses.
Absorption Line Spectrum are from cool gasses.
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DanKeitley
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(Original post by JamesWire)
This circuit is generally better. You can easily vary pd across component from 0 to maximum and it gives a wider range of resistance variations.
I realised I answered that question it in my post, you move the contact on the potential divider right...?
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viyas07
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(Original post by FaisalTreShah)
Absorption Spectrum: Dark lines, bright background.
Emission Spectrum: Bright lines, dark background.
Spectrum - Where ALL of the wavelengths/frequencies are present (in the radiation).

As photons are absorbed, they move UP the "energy level ladder".
As photons are emitted, they move DOWN the "energy level ladder".

That's all I've got to offer so far, hope this helps.


thanks,

which spectrums are from hot gases and which are from cool gases?

are absorption line spectrums from hot gases and emission from cool gases?
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FaisalTreShah
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(Original post by viyas07)
thanks,

which spectrums are from hot gases and which are from cool gases?

are absorption line spectrums from hot gases and emission from cool gases?
Emissions are hot.
Absorption are cool.

(Hopefully the colours should help you remember!)
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JamesWire
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(Original post by DanKeitley)
Ok thanks. How is the potential difference varied though? do you change the resistance of the resistor?
Sorry no, its not a resistor but a potentiometer (like a slider which can be moved to vary pd supplied to the appliance).
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motivatedshroom
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What are s and p seismic waves and do we need to know much about them (forgive me if the name's wrong, I have no clue! thanks guys


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motivatedshroom
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Also is this a good enough definition for phase difference: the measure of proportion of a cycle by how much two points on the same wave are 'out of sync'? Thanks


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rainbowsss
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(Original post by JamesWire)
This circuit is generally better. You can easily vary pd across component from 0 to maximum and it gives a wider range of resistance variations.


sorry to sound dumb but what does the rectangle with the arrow actually mean? what component is it?

thank you

** sorry
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Layontheland
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(Original post by rainbowsss)
sorry to sound dumb but what does the rectangle with the arrow actually mean? what component is it?

thank you

** sorry
Represents the potential divider. Can be drawn like:
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As far as I know

Hope it helps
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rainbowsss
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sorry could someone pleaseeee explain these answers to me?


and quick other question, if unpolarised light passes through a "polarise anaylser" , would the intesity of the light not change?
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rainbowsss
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(Original post by Layontheland)
Represents the potential divider. Can be drawn like:
Name:  potential-divider.jpg
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Size:  8.6 KBName:  img_full_46045.gif
Views: 131
Size:  1.9 KB
As far as I know

Hope it helps
thank you! so both the circuits mean the same thing?

Also, could you explain generally what a potential divider is? i've never really understood it

thank you
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