# Induced EMF graph of a very small wire moving through a coil

1. Apr 14, 2017

### FelaKuti

1. The problem statement, all variables and given/known data

2. Relevant equations

induced emf = - d(magnetic flux)/dt

3. The attempt at a solution

I believe the graph will start initially curving upwards, because it begins to cut more and more flux lines which lead to an increased induced emf. Once it is "fully" within the magnetic field, it will slope downwards to a negative induced emf as it begins to cut flux lines in the other direction. The peaks will have the same induced emf as the velocity is constant so the rate of change of flux should be equal for entering and leaving the coil. My solution was like this:

It's wrong, but I can't quite understand.

2. Apr 14, 2017

### kuruman

The loop is small which means it spends some time entirely between the poles of the magnet. While doing this, is the magnetic flux through it changing? If so, how?

3. Apr 14, 2017

### FelaKuti

I guess the magnetic flux isn't changing, because it's moving at a constant velocity. So that would mean no increase/decrease in the rate of change of magnetic flux, so no induced emf?

4. Apr 14, 2017

Yup.