# Homework Help: Electromagnetic induction for energy harvesting

1. Sep 6, 2010

### ddarvil

Hi there,
I'm currently working on a project that harnesses vertical motion via electromagnetic induction for the purpose of energy harvesting. I have built a prototype to confirm it's operation but haven't been able to figure out how to do the emf calculations. The device consists of a permanent magnet oscillating inside a plastic tube which has a copper winding (solenoid) on the outside. The winding consists of 1000 turns and the magnet is N42 neodymium.
After doing a reasonable search on the internet, I'm not sure how to procede. Can anyone help please?

I'm not looking for a solution but a concise idea of how I go about solving this problem. It seems I need to use faradays law (e = -N d_flux/d_t) which seems straight forward enough. emf direction is of no concern as the AC waveform is rectified. Is Faraday's law or Maxwell's equations easier for this type of problem?

The problem I'm having is representing the change in flux. Factors I assume are needed to be taken into account include:
1. The distance between the magnet and the coil
2. The velocity at which the magnet moves.
3. The changing incident angle of flux due to the magnets location with respect to the coil.

Any help or advice on how to obtain a symbolic solution (so I can change variables within my constraints to get the "best" solution) would be very much appreciated.