# A level physics help

Hi,I'm doing Edexcel IAL Physics AS.
Below is a description of what I understood of how potential difference is created across a circuit:
So,a battery contains imbalances of charges(electrons)on its terminals. The negative terminal(anode) has a surplus of electrons,as the anions lose electrons to become neutral,and the positive terminal(cathode) loses electrons,as the cations gains electrons to become neutral.This creates a region of high potential in the anode and a region of low potential in the cathode.So,if we add a wire now,the electrons would move from high potential to low potential.Now,we add a wire.Electrons now move from high potential to low potential.As the electrons now come back to the low potential(positive terminal of the battery),it loses energy.So,the battery now supplies energy to the electrons(emf) to create a potential difference again.The energy dissipated when electrons move through components(such as a light bulb),or obstalces(resistors),we call it the voltage.

Is my explanation correct?If I'm wrong somewhere,please do correct me!
(edited 9 months ago)
First of all, it's worth saying that understanding how a battery works is not easy, so kudos for trying, but I have highlighted below the parts where your explanation needs modifying.

Original post by Anlasan
...a battery contains imbalances of charges(electrons)on its terminals.

This is a common misconception, but the reason for the high potential at anode is a spontaneous chemical reaction which gives a driving force for producing electrons. However, the actual number (strictly, density) of electrons at the anode or cathode is very similar.

The negative terminal(anode) has a surplus of electrons,as the anions lose electrons to become neutral, ...

During the discharge cycle of battery, the anode is negative due to the production of cations and electrons. You may be thinking of an electrolytic cell, where anions lose electrons to become neutral (and thus the anode becomes positive terminal). In both cases, these are oxidation reactions (which is the definition of anode).

Now,we add a wire.Electrons now move from high potential to low potential.

Correct

As the electrons now come back to the low potential(positive terminal of the battery),it loses energy.So,the battery now supplies energy to the electrons(emf) to create a potential difference again.

That's almost right, but the units of potential difference are Volts = Joules/Coulomb, not energy. So, the energy supplied by battery is measured by the amount of charge (number of electrons) falling through a given potential difference.

The energy dissipated when electrons move through components(such as a light bulb),or obstalces(resistors),we call it the voltage.

No, the potential difference is given directly by the difference in potential between electrons at the anode and cathode. This can be related to the driving force (free energy) of the chemical reaction of the battery. No current needs to flow in order to measure a potential difference (which is called the open circuit voltage).
Original post by lordaxil
First of all, it's worth saying that understanding how a battery works is not easy, so kudos for trying, but I have highlighted below the parts where your explanation needs modifying.

This is a common misconception, but the reason for the high potential at anode is a spontaneous chemical reaction which gives a driving force for producing electrons. However, the actual number (strictly, density) of electrons at the anode or cathode is very similar.

During the discharge cycle of battery, the anode is negative due to the production of cations and electrons. You may be thinking of an electrolytic cell, where anions lose electrons to become neutral (and thus the anode becomes positive terminal). In both cases, these are oxidation reactions (which is the definition of anode).

Correct

That's almost right, but the units of potential difference are Volts = Joules/Coulomb, not energy. So, the energy supplied by battery is measured by the amount of charge (number of electrons) falling through a given potential difference.

No, the potential difference is given directly by the difference in potential between electrons at the anode and cathode. This can be related to the driving force (free energy) of the chemical reaction of the battery. No current needs to flow in order to measure a potential difference (which is called the open circuit voltage)

Oh!
Thank you very much for clarifying my mistakes!