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

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Reply 380

Joseph-

has anybody made a long answer / experiment pdf showing how to answer them?

Reply 381

blackstarz

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.

Reply 382

Dizzie31

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

Reply 383

JamesWire

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.

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...?

Reply 385

FaisalTreShah

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. :smile:

Reply 386

JamesWire

Original post by DanKeitley

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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Reply 387

DanKeitley

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?

Reply 388

Layontheland

Original post by FaisalTreShah

Damn... well, better to learn things late than never I suppose! Thank you for the correction. :smile:

No problem :smile:

Reply 389

FaisalTreShah

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!!!!!

Posted from TSR Mobile

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. :smile:

EDIT: Emission Line Spectrum are from hot gasses.
Absorption Line Spectrum are from cool gasses.

(edited 10 years ago)

Reply 390

DanKeitley

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...?

Reply 391

viyas07

Original post by FaisalTreShah

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?

Reply 392

FaisalTreShah

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!)

Reply 393

JamesWire

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).

(edited 10 years ago)

Reply 394

motivatedshroom

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! :smile:

thanks guys

Posted from TSR Mobile

Reply 395

motivatedshroom

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

Posted from TSR Mobile

Reply 396

rainbowsss

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

(edited 10 years ago)

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Reply 397

Layontheland

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:

As far as I know

Hope it helps :smile:

Reply 398

rainbowsss

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?