Physics: Post your doubts here!

[confused123]

Oct/Nov 2011/23 As level
Q1/ d
Q4/ (iv)
Help please :|

attach the link to the past paper plz.

 

[ultraviolet]

attach the link to the past paper plz.

I cant find the link for oct/nov 2011 p2 on the site

 

[confused123]

I cant find the link for oct/nov 2011 p2 on the site

then its unlikely that someone will be able to answer. you better write the question here..

 

[confused123]

http://www.xtremepapers.com/papers/...nd AS Level/Physics (9702)/9702_s11_qp_21.pdf
help required in 4 b ii part. and 7 b part. Thanks.

 

[CaptainDanger]

A? maybe experimental error which caused wrong mass to be calculate which resulted in difference in densities? caz atoms atoms per unit volume will remain same..share the correct option

I don't know the correct answer... It is C in one of the past year papers... But a few words have been added to this question which has changed it I think...

 

[Scafalon40]

Do you want to know how to solve it or u were just confirming if its a resistance wire?

Confirming.
Again, thank you.

 

[Hussnain]

http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Physics (9702)/9702_s05_qp_4.pdf
2(b)(ii).
3(b)(ii)
4(c)(i)
6(b)
7(a),(b) Please answer my questions

 

[anonymous123]

hi bro,
from where did u took this question ? is this answer really correct. i learned the formula in the cambrdige book which says in this case => AB/ AC into Eo i.e .65/1 into 12 = 7.8 Volt.

but here i see a different situation where first we divided ab length with total length and then multiplied with the total resistance of the wire. this gave us resistance across AB wire,

then we used this resistance to find the unknown e.m.f. of the test cell is this whole formula correct in the image?

in the revision section go to dc circuits its the last problem there..

 

[anonymous123]

It is called the "Potential Difference across the resistor ". So if 1 end of the resistor has a potential of 3 V and the potential difference is 6.75, then:
3-x= 6.75
x= 3 - 6.75

Concerning the potential divider question:

I'm not entirely sure of this answer but I understand that since the galvanometer is indicating a zero current, therefore the potential difference between the positive plate and B is zero ( same with the negative plate and A ). Why? Because if there was a potential difference there should be a current passing. This does mean that the potential difference across AB is equal to the potential difference across the cell being tested. Thus, you simply need to find the P.D. across AB.

By using ratio of length to resistance, we get the resistance of AB. Then again by using ratio of resistance to P.D. we get the P.D. across AB.

1 ---> 60
0.65 ---> ?

Then

60 + 20 ---> 12
39 ---> ?

Hope this helped. : )

Jazakallah tht helped!!

just one thing why did u add 60+20?

 

[CaptainDanger]

A? maybe experimental error which caused wrong mass to be calculate which resulted in difference in densities? caz atoms atoms per unit volume will remain same..share the correct option

Yes it is A...

 

[Idolfanatic95]

Aoa, Is there any possibility that i might get solved paper 1 of physics in here? year 2002-09. . .There're so many mcqs im confused about :/

 

[DragonCub]

Yes it is A...

But I think A and C are both correct.
The density, or total mass per unit volume, is equal to mass per atom × number of atoms per unit volume.
P's density is greater than Q's, so MpNp>MqNq.
And it says Np=Nq, so Mp>Mq.

 

[omg]

http://www.xtremepapers.com/papers/...and AS Level/Physics (9702)/9702_s07_qp_5.pdf
what is the method of finding when the terminal velocity has reachedd??????????????

 

[DragonCub]

http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Physics (9702)/9702_s05_qp_4.pdf
2(b)(ii).
3(b)(ii)
4(c)(i)
6(b)
7(a),(b) Please answer my questions

 

[waleedsmz]

Jazakallah tht helped!!

just one thing why did u add 60+20?

U're welcome dude. ; )

Why did I add the 20? Well, let's think of another circuit with only a 12 V cell, a 60 ohm resistor and a 20 ohm resistor all connected in series. How would you calculate the resistance on the 60 ohm resistor? You'd say that the 12 V is shared with all the resistors in the circuit and thus:

20 + 60 ---> 12
60 ---> ?

In your question, it's exactly the same situation, the only difference is that you're getting the resistance of a part of the line AC ( the 60 ohm resistor ), i.e. the 39 ohms. It's as if you divided the line AC into two separate resistors so now you have a 39 (AB), a 21 (BC) and a 20 ohm resistors in the circuit. How to get the voltage across 39?

39 + 21 + 20 ---> 12
39 ---> ?

Hope that helped. : )

 

[waleedsmz]

Minimum will be zero . i am not sure bout this but maybe when the jockey is move towards the extreme position then the voltage or resistance might bcm zero then current will be zero as well :/ plz someone else clarify. Thanks

I believe when the jockey moves to the left, the lamp would actually be shorted. Meaning that no current will pass through the lamp as there is a negligible resistance in the upper wire of the lower loop ( Indicated by the red straight line ).

​

By the way, thanks for explaining why it will have that maximum value because I didn't know it. xD
Hope this helped. : )

 

[anonymous123]

U're welcome dude. ; )

Why did I add the 20? Well, let's think of another circuit with only a 12 V cell, a 60 ohm resistor and a 20 ohm resistor all connected in series. How would you calculate the resistance on the 60 ohm resistor? You'd say that the 12 V is shared with all the resistors in the circuit and thus:

20 + 60 ---> 12
60 ---> ?

In your question, it's exactly the same situation, the only difference is that you're getting the resistance of a part of the line AC ( the 60 ohm resistor ), i.e. the 39 ohms. It's as if you divided the line AC into two separate resistors so now you have a 39 (AB), a 21 (BC) and a 20 ohm resistors in the circuit. How to get the voltage across 39?

39 + 21 + 20 ---> 12
39 ---> ?

Hope that helped. : )

such a clear explanation ofc it helped Jazakallah again..

 

[waleedsmz]

http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Physics (9702)/9702_s07_qp_5.pdf
what is the method of finding when the terminal velocity has reachedd??????????????

What is your apparatus first? For instance, mine was that you drop a ball into a measuring cylinder ( or a large tube ) full of oil. I believe you can't be 100 % sure that a certain ball will reach a terminal velocity, however you can check it. You can mark two equal distances from the bottom of the tube, like 5 cm each. Why the bottom? To make sure that the terminal velocity has been reached and that there is no more acceleration. Then you measure the time taken to fall through the two distances separately. Let's call them AB and BC. If the time taken for AB is the same as BC then there is no acceleration and the speed is constant ( terminal ). I honestly don't know what would you do if the time is different. Maybe you'll have to choose a larger tube/ a more dense liquid/ smaller balls and repeat the experiment.

Hope that helped. : )

 

[Hussnain]

View attachment 7420View attachment 7423

THANKS

 

[omg]

What is your apparatus first? For instance, mine was that you drop a ball into a measuring cylinder ( or a large tube ) full of oil. I believe you can't be 100 % sure that a certain ball will reach a terminal velocity, however you can check it. You can mark two equal distances from the bottom of the tube, like 5 cm each. Then you measure the time taken to fall through the two distances separately. Let's call them AB and BC. If the time taken for AB is the same as BC then there is no acceleration and the speed is constant ( terminal ). I honestly don't know what would you do if the time is different. Maybe you'll have to choose a larger tube/ a more dense liquid/ smaller balls and repeat the experiment.

Hope that helped. : )

im still nt clear how 2 gt the terminal velocity :/