# Measuring of electrode potential.

## Main Question or Discussion Point

In set-up with two half-cells and a voltmeter, the potential difference is measured using the voltmeter.
But voltmeter has high resistance,which i know is still able to measure potential difference,but wouldnt it prevent electrons from flowing
What i meant was,the use of voltmeter creates a 'open circuit' which prevents electron flow and hence reaction in the two half cell will not take place?
But my teacher says that reaction takes place in both half cell,which meant that there is electron transfer and redox??
Does this have to do with some physics regarding voltmeter??

## Answers and Replies

Borek
Mentor
Voltmeter closes the circuit, it doesn't leave the circuit open. What voltmeter does it measures the current flowing through a known resistance, then it displays the result as potential (V=RI).

Actually it is not a chemistry question, but physics question - how does the voltmeter work and what happens in the circuit with a voltmeter (doesn't matter if it is a battery powered circuit or some other kind).

Voltmeter closes the circuit, it doesn't leave the circuit open. What voltmeter does it measures the current flowing through a known resistance, then it displays the result as potential (V=RI).

Actually it is not a chemistry question, but physics question - how does the voltmeter work and what happens in the circuit with a voltmeter (doesn't matter if it is a battery powered circuit or some other kind).
So the high resistance of voltmeter must play a role.what if there is no voltmeter,for instance just a strip wire...is experiment the same?
Btw wouldn't the high resistance prevent current from flowing or something like that??

Borek
Mentor
Please read how voltmeter works and how it measures the potential difference, your questions are directly answered by the theory behind it. Most likely any general physics book will do.

You can't understand potential measurement without good understanding what a potential difference is and how it is related to the charge, and what happens when you close the circuit - that's all physics.