Tech Battery Basics: Understanding the Flow of Electrons and Energy

[digital_biscu]

Hi All

Currently studying for a Subject Enhancement Course prior to starting a PGCE and I am struggling with the Electricity side of things! Something I also struggled with at A-Levels myself many years ago...

My query is how does batteries work. I understand the model whereby electrons are generated at the anode and used at the cathode and when you place a circuit between these then there is a flow of electrons. However, lots of websites state that the anode and cathode sit in the same electrolyte, some with separators which allow ions through. Surely then, if this is the case there will just be a flow of electrons from the anode to the cathode inside the battery and adding any type of circuit would be fruitless? So, which model is correct and if it is the latter, please explain to me how it actually works?

Secondly, I am guessing that the electrons have energy and it is this that is used up in components such as lights etc. I know this is "Electrical Potential Energy" but is there anything more specific to describe the energy? Also, how would an electron before a bulb be different from one after a bulb? And finally, if there are 3 bulbs in a series circuit how would the electrons know to only give up a third of that energy?

Many thanks in advance and sorry for the epic amount of questions!
Digi

 

[Drakkith]

No, it only allows positive ions to move through it. The electrons move through the circuit. This article explains it in a little bit of detail: http://en.wikipedia.org/wiki/Galvanic_cell

Secondly, I am guessing that the electrons have energy and it is this that is used up in components such as lights etc. I know this is "Electrical Potential Energy" but is there anything more specific to describe the energy?

Applying a voltage to the circuit generates an EMF that causes the electrons to move. It is what gives them the energy needed to perform the work the circuit will do. Consider the very simple case of an electron placed near an electrode. If we then apply a negative charge to the electrode the electron will experience a force that moves it away from the electrode. This is what is meant by "Electrical Potential Energy". When we applied the negative charge the electron acquired potential energy that was converted into kinetic energy as the electron accelerated away from the electrode. This moving electron can then perform work on something.

In a circuit the same basic rules apply. We apply a voltage which generates an EMF in the circuit which causes electrons to move. These moving electrons have energy and generate fields that can be used to perform work. This of course requires energy which we are providing by the voltage source.

Also, how would an electron before a bulb be different from one after a bulb? And finally, if there are 3 bulbs in a series circuit how would the electrons know to only give up a third of that energy?

It would not be different. I'm not sure how to explain it though.