Biology; Chemistry; Physics: Post your doubts here!

[Mahnoorfatima]

http://papers.xtremepapers.com/CIE/Cambridge International O Level/Physics (5054)/5054_s13_qp_12.pdf
Question 34?

 

[M.Omar]

oops wrong file sorry

this one

It,s 5.2
In case ur wondering tht the question need to be stated correctly for c part by writing tht newton meter is removed so tht the 2 forces 1.2 and 4N can be added,then tht wud be wrong.Newton meter is not applying force on it,s own infact it is just holding the weight steady.It cancels out it,s moment by resisting the moment and registering the force required to do so but it does not cancel it,s weight and so the 2 forces are simply added.On the contrary I personally don't think it,s such a cake of a question..the tricky part can vwery well be seen

 

[Dark Destination]

http://papers.xtremepapers.com/CIE/Cambridge International O Level/Physics (5054)/5054_s13_qp_12.pdf
Question 34?

B?

 

[princess Anu]

http://papers.xtremepapers.com/CIE/Cambridge International O Level/Physics (5054)/5054_w05_qp_1.pdf
In question 1 the S scale should be 2.34 , no ? how do we know when to consider the small space between two marks in the reading as well? i hope you get me ?

 

[FLRNAB]

It,s 5.2
In case ur wondering tht the question need to be stated correctly for c part by writing tht newton meter is removed so tht the 2 forces 1.2 and 4N can be added,then tht wud be wrong.Newton meter is not applying force on it,s own infact it is just holding the weight steady.It cancels out it,s moment by resisting the moment and registering the force required to do so but it does not cancel it,s weight and so the 2 forces are simply added.On the contrary I personally don't think it,s such a cake of a question..the tricky part can vwery well be seen

If you remove 4N then the meter rule would still balance because the pivot exerts the force of 1.2N upwards on the center of mass of the rule. Doesn't newton meter show the force needed to cancel the moment of 4N only?

 

[Awesome12]

http://papers.xtremepapers.com/CIE/Cambridge International O Level/Physics (5054)/5054_s13_qp_12.pdf
Question 34?

Since the filament has broken, less current will decrease, thus the reading on the ammeter decreases. There will be a decrease in the voltage across L2. Since the voltage is decreasing across L2, it will increase across L1, and the option is B

 

[Dark Destination]

Since the filament has broken, the current flowing through it will be 0, thus the reading on the ammeter decreases. There will be a decrease in the voltage across L2. Since the voltage is decreasing across L2, it will increase across L1, and the option is B

But you said reading on Ammeter decreases, that's not B. :/

 

[Awesome12]

But you said reading on Ammeter decreases, that's not B. :/

B is
reading on ammeter decrease
Reading on voltmeter increases

 

[Dark Destination]

B is
reading on ammeter decrease
Reading on voltmeter increases

If the filament breaks won't that stop the current flowing completely? The circuit would be off. :/

 

[Mahnoorfatima]

If the filament breaks won't that stop the current flowing completely? The circuit would be off. :/

I don't get this crap!

 

[Dark Destination]

I don't get this crap!

Is the answer B on not?

 

[Awesome12]

If the filament breaks won't that stop the current flowing completely? The circuit would be off. :/

Exactly, I did mention it. The question asks about the ammeter, and it decreases

 

[Mahnoorfatima]

Is the answer B on not?

It is.

 

[Dark Destination]

It is.

When the filament breaks, the current does not flow through the lamp.
Instead it flows through the voltmeter, which is now measuring the potential difference of the whole circuit, and will register a greater reading.

And the Voltmeter has a high resistance, so that increases the total resistance of the circuit, which causes the current to reduce and the ammeter reading decreases.

That's what i think happens :/

 

[funky brat]

B?

Won't it be C? :/

 

[Dark Destination]

Won't it be C? :/

What's C?

 

[funky brat]

When the filament breaks, the current does not flow through the lamp.
Instead it flows through the voltmeter, which is now measuring the potential difference of the whole circuit, and will register a greater reading.

And the Voltmeter has a high resistance, so that increases the total resistance of the circuit, which causes the current to reduce and the ammeter reading decreases.

That's what i think happens :/

How can it measure the potential difference of the whole circuit?

 

[Dark Destination]

How can it measure the potential difference of the whole circuit?

I'm just philosoph-isizing.
I have no idea how it's B. But that is the only logical explanation. If the filament breaks, the current will flow through the voltmeter, lol.

What awesome12 said makes no sense at all. =.=

 

[funky brat]

What's C?

When filament breaks, it's resistance decreases do voltmeter reading decreases, while the ammeter is measuring the current in the whole circuit, so as the resistance decreases more current flows hence ammeter reading increases. :/

 

[FLRNAB]

When filament breaks, it's resistance decreases do voltmeter reading decreases, while the ammeter is measuring the current in the whole circuit, so as the resistance decreases more current flows hence ammeter reading increases. :/

The volt meter always has a very high resistance because it needs to measure the p.d across a component and to do that current needs to pass through the component and not through the voltmeter. This will only happen when electricity finds it easier to flow through the component.