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

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#881

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Omg, why don't they?

**Gotzz**)Omg, why don't they?

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#882

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No. It was definitely 1000 and 1500

there was 0.02 amps of current going towards the 750 ohm resistor, so that works out to be 15v. In parallel, voltage is equal so R2 will have 15v in it too. From the diagram you knew 0.01 amps of current went to R2, 15/0.01=1500 resistance in R2 is 1500 ohms

to work out resistance in parallel:

1/750 + 1/1500 = 1/R, solve to find R and you get the combined resistance of the two in parallel= 500. Now lets call total resistance in the circuit 500+x, where x is R1,

current was 0.03 and total voltage was 45, so 45/0.03=total resistance=1500

1500=x+500, x is 1000 ohms, and x is R1

hope that's enough evidence for you guys.

**Hamster96**)No. It was definitely 1000 and 1500

there was 0.02 amps of current going towards the 750 ohm resistor, so that works out to be 15v. In parallel, voltage is equal so R2 will have 15v in it too. From the diagram you knew 0.01 amps of current went to R2, 15/0.01=1500 resistance in R2 is 1500 ohms

to work out resistance in parallel:

1/750 + 1/1500 = 1/R, solve to find R and you get the combined resistance of the two in parallel= 500. Now lets call total resistance in the circuit 500+x, where x is R1,

current was 0.03 and total voltage was 45, so 45/0.03=total resistance=1500

1500=x+500, x is 1000 ohms, and x is R1

hope that's enough evidence for you guys.

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#883

can someone please tell me how you did the resistivity one?? also what did everyone else get for the path difference??

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#884

**Hamster96**)

No. It was definitely 1000 and 1500

there was 0.02 amps of current going towards the 750 ohm resistor, so that works out to be 15v. In parallel, voltage is equal so R2 will have 15v in it too. From the diagram you knew 0.01 amps of current went to R2, 15/0.01=1500 resistance in R2 is 1500 ohms

to work out resistance in parallel:

1/750 + 1/1500 = 1/R, solve to find R and you get the combined resistance of the two in parallel= 500. Now lets call total resistance in the circuit 500+x, where x is R1,

current was 0.03 and total voltage was 45, so 45/0.03=total resistance=1500

1500=x+500, x is 1000 ohms, and x is R1

hope that's enough evidence for you guys.

Oh well, it was only 2 marks

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#885

Can anyone remember the questions? Ill try to make an unofficial mark scheme if people can?

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#886

(Original post by

I would be over the MOON with a C I got an A in my coursework and a U in the January exam, even though I did every single past paper to death and did so much revision for it

**leahcee**)I would be over the MOON with a C I got an A in my coursework and a U in the January exam, even though I did every single past paper to death and did so much revision for it

But that's only for AS, A2 is suppose to be much harder so it's likely to even go down to a D :/

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#887

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Fair enough, I saw you had Bio 2, Chem 2, and Physics 2 all within the space of a few days! How did you manage?

**Boy_wonder_95**)Fair enough, I saw you had Bio 2, Chem 2, and Physics 2 all within the space of a few days! How did you manage?

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#888

Here is my reasoning with why R1 is 1000 and R2 is 1500:

We know that the p.d across R1 is 30V (45-15). So we know the expected p.d result (Vout) from a potential divider equation should be 30V.

The combination of the other two resistances in parallel will therefore need to make 500 when calculated, so that when you use the potential divider equation on R1, you get 30V, shown here:

Vout=R1/(R1+R2) *Vin

Note that R1 here does represent R1 in the circuit but R2 represents the resistance of the combo (R2 and the 750ohm Resistor)

So, we get: 30=1000/(1000+500) *45, which works.

Now that we know what the combination resistance needs to equal (500), we know that 1/500= 1/750 + 1/R2

Therefore 1/R2 = 1/1500 and R2 = 1500ohms

Does this clear things up for people? If there is another way to prove a different answer then please post it

Posted from TSR Mobile

We know that the p.d across R1 is 30V (45-15). So we know the expected p.d result (Vout) from a potential divider equation should be 30V.

The combination of the other two resistances in parallel will therefore need to make 500 when calculated, so that when you use the potential divider equation on R1, you get 30V, shown here:

Vout=R1/(R1+R2) *Vin

Note that R1 here does represent R1 in the circuit but R2 represents the resistance of the combo (R2 and the 750ohm Resistor)

So, we get: 30=1000/(1000+500) *45, which works.

Now that we know what the combination resistance needs to equal (500), we know that 1/500= 1/750 + 1/R2

Therefore 1/R2 = 1/1500 and R2 = 1500ohms

Does this clear things up for people? If there is another way to prove a different answer then please post it

Posted from TSR Mobile

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#889

(Original post by

But that's only for AS, A2 is suppose to be much harder so it's likely to even go down to a D :/

**Room4student**)But that's only for AS, A2 is suppose to be much harder so it's likely to even go down to a D :/

I think the content of Unit 5 is alot more interesting, no idea what the exam is going to be like but overall A2 has been better.

Plus, after getting the results from AS I have worked so much harder!

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#890

**Hamster96**)

No. It was definitely 1000 and 1500

there was 0.02 amps of current going towards the 750 ohm resistor, so that works out to be 15v. In parallel, voltage is equal so R2 will have 15v in it too. From the diagram you knew 0.01 amps of current went to R2, 15/0.01=1500 resistance in R2 is 1500 ohms

to work out resistance in parallel:

1/750 + 1/1500 = 1/R, solve to find R and you get the combined resistance of the two in parallel= 500. Now lets call total resistance in the circuit 500+x, where x is R1,

current was 0.03 and total voltage was 45, so 45/0.03=total resistance=1500

1500=x+500, x is 1000 ohms, and x is R1

hope that's enough evidence for you guys.

Posted from TSR Mobile

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#891

(Original post by

was the current not 0.030, 0.020 ect? so you would get a voltage of 15V for the fourth question?

**hannahsm**)was the current not 0.030, 0.020 ect? so you would get a voltage of 15V for the fourth question?

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#892

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Sigh, I thought really hard about the question and then you go ahead and beat me to it but thanks

Posted from TSR Mobile

**OllieGCSEs**)Sigh, I thought really hard about the question and then you go ahead and beat me to it but thanks

Posted from TSR Mobile

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#893

(Original post by

Yeah we all got 0.3

**Gotzz**)Yeah we all got 0.3

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#895

(Original post by

I personally found Unit 4 to be alot nicer than Unit 2.

I think the content of Unit 5 is alot more interesting, no idea what the exam is going to be like but overall A2 has been better.

Plus, after getting the results from AS I have worked so much harder!

**Gcayte**)I personally found Unit 4 to be alot nicer than Unit 2.

I think the content of Unit 5 is alot more interesting, no idea what the exam is going to be like but overall A2 has been better.

Plus, after getting the results from AS I have worked so much harder!

That's why i would like to carry on with physics, i heard it involves solar system in A2 which i would find interesting but exams in physics are in my opinion the hardest and Uni's require A's and B's so a C in AS does not sound like enough to carry on but we'll see, good luck in your remaining exams man!

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#898

(Original post by

I got 1060?

**Gotzz**)I got 1060?

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#899

(Original post by

what did you do to get 0.3? feeling stupid now haha also what did you get for the path difference one??

**charlotteg96**)what did you do to get 0.3? feeling stupid now haha also what did you get for the path difference one??

Which path difference one, sorry?

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#900

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It was 2*the wavelength then divide by 1*10^-9

**Loiks94**)It was 2*the wavelength then divide by 1*10^-9

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