Microphones?

What's the physical difference between a condenser, and a dymanic?

Condensers work by changing the capacitance between two plates, one of which is the diaphragm.
Dynamics use the moving coil around the diaphragm to create induction.
http://en.wikipedia.org/wiki/Microphone

I did a 2 yr course in Snd Eng and I agree with Jon Soundman

A great reference and handy book to have around is "The Sound Reinforcement Handbook" by Yamaha.

It contains a weath of information on all kinds of audio equipment and especially mics. You'll find definition of types and guidlines for application of specific mics as well as graphs detailing the dynamic responses of all but the most obscure microphones.

You can find it in a music store or Amazon. It is an invaluble resource.