Calculating Voltage in a Battery: Answers to Your Questions

[Amyriel]

Hi :)
It might seems a stupid question but I can't find any answer for it ^^

I have a question: how voltage is calculated in a battery?

Let's say you create a battery with - 1 C of charge of electrons on the and the other side + 1 C of charge, could you tell me what is the voltage of this battery? According to Coulombs law the force F needed is (kQ1Q2)/distance² If we keep this track the potential energy W = F X distance which will give us kQ1Q2/distance, so voltage is still distance dependent, right? Is it calculated from a mean distance between the two terminals (like the middle of each cell?)

Thanks for your help!

 

[Svein]

I have a question: how voltage is calculated in a battery?

That is an effect of the potential of the metals and chemicals used. Take a piece of steel and a piece of aluminum, connect wires to them and lower them into the sea (not the freshwater kind) a couple of centimeters apart. You have now created a battery, it is able to drive a current through an amperemeter.

 

[Drakkith]

Thats not how a battery works. Batteries don't separate charges like a capacitor does. They use chemical reactions to create a voltage. Each electrochemical cell's voltage depends entirely on what its made of. There are charts and tables all over the net that can tell you the voltage for a particular type of cell.

 

[CWatters]

Don't feel stupid...
http://en.wikipedia.org/wiki/Battery_(electricity )

Volta did not appreciate that the voltage was due to chemical reactions. He thought that his cells were an inexhaustible source of energy,[6] and that the associated corrosion effects at the electrodes were a mere nuisance, rather than an unavoidable consequence of their operation, as Michael Faraday showed in 1834

The voltage developed across a cell's terminals depends on the energy release of the chemical reactions of its electrodes and electrolyte. Alkaline and zinc–carbon cells have different chemistries, but approximately the same emf of 1.5 volts; likewise NiCd and NiMH cells have different chemistries, but approximately the same emf of 1.2 volts.[17] The high electrochemical potential changes in the reactions of lithium compounds give lithium cells emfs of 3 volts or more.[/quote]

 

[Amyriel]

Thank you so much! I know now where I need to look at :)

 

[sophiecentaur]

so voltage is still distance dependent, right?

Not right, as a general principle. Voltage is PotentiaL Difference, which does not depend on distance apart of battery plates or length of wire. It depends upon the Energy that's been given to Charges (Volts = Joules per Coulomb).
It is true that, for a particular Field (=Volts per Metre) then the PD across two points in that field will be dependent on their separation. But that is not relevant to batteries - unless increasing distance involves inserting more battery cells in series.