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VCE Stuff => VCE Science => VCE Mathematics/Science/Technology => VCE Subjects + Help => VCE Physics => Topic started by: kenhung123 on April 02, 2010, 02:07:13 pm

Title: Voltmeters - High restistance, high voltage, low current?
Post by: kenhung123 on April 02, 2010, 02:07:13 pm
Ok so voltmeters has high resistance to reduce the current flow into the voltmeter itself. But doesn't this mean a large voltage is drawn into the voltmeter and less through the circuit element?
Title: Re: Voltmeters - High restistance, high voltage, low current?
Post by: kenhung123 on April 02, 2010, 02:23:39 pm
Where I is very small as R is very big
Where I is very small and R is very big and therefore V is neutral

Title: Re: Voltmeters - High restistance, high voltage, low current?
Post by: Edmund on April 02, 2010, 03:38:14 pm
Voltmeters have a really high resistance, so little current will flow in the direction where there is a voltmeter. High resistance means small voltage current because voltage current is inversely proportional to resistance. Current Voltage remains constant, flow of charge is not changing due to fixed amount of charge from power source.
Title: Re: Voltmeters - High restistance, high voltage, low current?
Post by: kenhung123 on April 02, 2010, 04:00:23 pm
Hmm so R=V/I when R is very large and I is constant so won't V increase?
Title: Re: Voltmeters - High restistance, high voltage, low current?
Post by: kyzoo on April 02, 2010, 04:30:58 pm
Quote from: kenhung123 on April 02, 2010, 02:07:13 pm
Ok so voltmeters has high resistance to reduce the current flow into the voltmeter itself. But doesn't this mean a large voltage is drawn into the voltmeter and less through the circuit element?

Voltmeters are always connected in parallel to the circuit element. Parallel components will draw equivalent voltages from the EMF. So if there is a 6V battery, and the voltmeter is connected in parallel to the circuit element, both the voltmeter and circuit element will receive 6 volts.

Furthermore as Edmund has said, the resistance of the voltmeter is very high so it draws very little current.

As a result, the effect that the voltmeter has on the normal operations of the circuit is minimized.
Title: Re: Voltmeters - High restistance, high voltage, low current?
Post by: Edmund on April 02, 2010, 05:06:36 pm
Oops sorry, I mixed up some terms... I've fixed the post above
Title: Re: Voltmeters - High restistance, high voltage, low current?
Post by: physics on April 02, 2010, 09:13:50 pm
our school just started electricity ...i think we're kinda behind compared to whatever part of electricity ur going on about  O__O
just one question in electricity do we talk about electron flow or current cause i know they go in opposite directions
current is + to -
and electron is - to + right?
:D just clarifying
Title: Re: Voltmeters - High restistance, high voltage, low current?
Post by: kenhung123 on April 02, 2010, 09:37:16 pm
We talk about conventional current + to -
Title: Re: Voltmeters - High restistance, high voltage, low current?
Post by: kyzoo on April 02, 2010, 11:22:44 pm
Quote from: annahinh on April 02, 2010, 09:13:50 pm
our school just started electricity ...i think we're kinda behind compared to whatever part of electricity ur going on about  O__O

xD our school is way behind, we still have to do detailed study chapter (which we haven't started yet) before we even touch electricity. I was just using my 1/2 knowledge base lol.
Title: Re: Voltmeters - High restistance, high voltage, low current?
Post by: kenhung123 on April 02, 2010, 11:26:21 pm
Really? I thought you guys would have finished the course by now..
Title: Re: Voltmeters - High restistance, high voltage, low current?
Post by: kyzoo on April 02, 2010, 11:32:14 pm
Quote from: kenhung123 on April 02, 2010, 11:26:21 pm
Really? I thought you guys would have finished the course by now..

Nah, our school is very very very very slow in going through the study design. For Spesh, we've only done chapters 2 and 4 when chapter 1, 3 and 5 should also have been done.