Incoming Flux? Outgoing Flux?

1. Mar 15, 2005

Geoffrey F. Miller

Okay. Lets say you have a coil. You drop a magnet through it, which induces an emf (please explain what exactly an emf is). So, somehow Faraday's Law of Induction comes into play (please explain this law to me). Now you have an incoming and outgoing flux, right (I have no idea what this means)? I'm guessing that the incoming and outgoing flux are equal but opposite. Am I correct? What are the units of a flux? Why are the fluxes equal, that is, if they really are?

2. Mar 15, 2005

Andrew Mason

Most of your questions can be answered by carefully reading your text. At least that would give you some basic knowledge to build on.

An emf (archaic terminology meaning electo-motive force) is simply an induced potential difference or voltage between two points. Flux, or lines of force, is a purely geometrical model that helps us to think about magnetic fields. It not physically real.

If you think about lines of force around the magnet cutting across the loops of the wire, Faraday's law says that this induces (creates at a distance) a potential difference between the ends of the wire. The incoming and outgoing fluxes may be equal and opposite but they 'cut' at different times so the potential difference across the wires is in one direction as the magnet approaches the center of the coil and the other direction as it leaves.

AM