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Why should voltmeter readings be taking straight after completing the circuit?
Original post by hatsuko
Why should voltmeter readings be taking straight after completing the circuit?
Welcome to TSR.

Interesting question, but to give a correct response will need a context.

Have you asked because you are following the instructions for an experiment or is it to do with a specific question you are attempting to answer?

If you post the full question here it will help greatly.
Reply 2
Original post by uberteknik
Welcome to TSR.

Interesting question, but to give a correct response will need a context.

Have you asked because you are following the instructions for an experiment or is it to do with a specific question you are attempting to answer?

If you post the full question here it will help greatly.

it's actually a chemistry but question, but I thought it would be better here.
I constructed a cell made of two half cells, i completed the circuit and need to know why i need to take the reading straight away
I asked there yesterday but nobody could help
Original post by hatsuko
it's actually a chemistry but question, but I thought it would be better here.
I constructed a cell made of two half cells, i completed the circuit and need to know why i need to take the reading straight away
I asked there yesterday but nobody could help

OK understood.

Primary cells produce electrical current (flow of electrons) by exploiting chemical reactions caused by ionic bonding between elements (reduction and oxidation). Specifically those elements with a charge imbalance caused by either an excess or deficit of electrons in the valence shell.

i.e. the bond is formed by electrostatic charge attraction through excess electrons (-ve charge) of one atom and a deficit of electrons (more protons causing a +ve charge) of another atom.

When ionic bonds are formed from neutral atoms, there is a transfer of charge (electrons) between one atom and another.

That charge transfer is facilitated via a conduction path (circuit) and as soon as the circuit is created, the chemical reaction begins. After a time the chemical reaction will be complete and no further charge will transfer.

Voltage is defned as the amount of energy each Coulomb of charge carries during the redox reaction.

So the voltage must be measured as soon as the circuit is created because that is when the redox reaction commences (most vigorous) and as the reaction continues, the voltage must fall because the reactants are continuously depleting from that point onwards. The voltage will fall to zero when the reaction is complete.

Are you OK with this explanantion?
(edited 10 years ago)

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