Biology; Chemistry; Physics: Post your doubts here!

[Dark Destination]

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. :/

But that person said B is the right answer

 

[Dark Destination]

What the hell is this?

What if we connect a voltmeter in SERIES, with a bulb? What will be the reading?
Will the reading be the EMF of the bulb?

Will the reading be the same, if we connect the BATTERY, directly to the voltmeter?

 

[funky brat]

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.

So you mean when the filament breaks, now current will pass through voltmeter which has a very high resistance so ammeter reading decreases?

 

[Muhammad_Hamza]

B part (ii)

 

[M.Omar]

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?

Yup it does show the force required to have resultant moment zero..To further complement ur statement if the newton meter were to be exactly below the line of weight of tht block it wud cancel it,s weight as well and then (even including the block) the force wud be 1.2
U r also right when u say if we remove the weight the pivot exerts 1.2N coz it wud then have to cancel only weight of ruler

 

[Dark Destination]

So you mean when the filament breaks, now current will pass through voltmeter which has a very high resistance so ammeter reading decreases?

Wow. :O

What type of question is this? .-.

 

[FLRNAB]

So you mean when the filament breaks, now current will pass through voltmeter which has a very high resistance so ammeter reading decreases?

Yes. Resistance is inversely proportional to current given that temperature remains constant.

There is no other path for current to flow as the filament has broken which is essentially a wire of tungsten in the bulb so current has to flow through the voltmeter which has very high resistance compared to the bulb so reading on ammeter will decrease.

 

[funky brat]

Yes. Resistance is inversely proportional to current given that temperature remains constant.

There is no other path for current to flow as the filament has broken which is essentially a wire of tungsten in the bulb so current has to flow through the voltmeter which has very high resistance compared to the bulb so reading on ammeter will decrease.

So what about potential difference?

 

[funky brat]

Wow. :O

What type of question is this? .-.

I was just repeating his words to make sure I'm getting the right thing. -.-

 

[Dark Destination]

So the VOLTMETER displays a ZERO READING in series. What philosophy is this. O_O

 

[***amd***]

What the hell is this?

What if we connect a voltmeter in SERIES, with a bulb? What will be the reading?
Will the reading be the EMF of the bulb?

Will the reading be the same, if we connect the BATTERY, directly to the voltmeter?

perhaps it will show the emf of battery.

 

[M.Omar]

So what about potential difference?

It increases since the resistance of voltmeter is really high (higher than lamp of course) and as it measures the potential difference btw 2 points(which are still intact)
the Charges loses a lot of electric potential as it passes thru voltmeter giving a high p.d(electric potential refers to energy expended (and u can check this by applying P=I*R)
Understsament:Hih resitance implies higher p.d

 

[Dark Destination]

perhaps it will show the emf of battery.

But their will be a bulb in the circuit too.
Will the reading still be the EMF :/

 

[FLRNAB]

So the VOLTMETER displays a ZERO READING in series. What philosophy is this. O_O

So what about potential difference?

See this:
http://www.furryelephant.com/player.php?subject=physics&jumpTo=ee/5Ms20

Deeper section.

 

[M.Omar]

So the VOLTMETER displays a ZERO READING in series. What philosophy is this. O_O

No lol
It will infact be really high close to power supply provided it is the only load ootherwise just really high

 

[***amd***]

But their will be a bulb in the circuit too.
Will the reading still be the EMF :/

khana khanay do

 

[Faizan Muhammmad]

So the VOLTMETER displays a ZERO READING in series. What philosophy is this. O_O

it does not
it gives the emf of the cell

 

[funky brat]

It increases since the resistance of voltmeter is really high (higher than lamp of course) and as it measures the potential difference btw 2 points(which are still intact)
the Charges loses a lot of electric potential as it passes thru voltmeter giving a high p.d(electric potential refers to energy expended (and u can check this by applying P=I*R)
Understsament:Hih resitance implies higher p.d

Oh, I got that. Thanks.

 

[Dark Destination]

khana khanay do

Okay, maths master.

 

[Dark Destination]

it does not
it gives the emf of the cell

But a BULB is in the circuit too. Will it still be the EMF?