How does electro dynamical instruments work?

[0fibonacci1]

I know that electro dynamical instrument has moving coil and stationary coil, and moving coil moves around it, does stationary coil make homogenic magnetic field? And moving coil moves around axis, and we have coil springs where they are placed and what they do? In instrument with moving coil we use aluminuim as a break, but in electro dynamical we use air pressure where is it placed? Correct me if I was wrong somewhere and explain how it properly works.

 

[berkeman]

I know that electro dynamical instrument has moving coil and stationary coil, and moving coil moves around it, does stationary coil make homogenic magnetic field? And moving coil moves around axis, and we have coil springs where they are placed and what they do? In instrument with moving coil we use aluminuim as a break, but in electro dynamical we use air pressure where is it placed? Correct me if I was wrong somewhere and explain how it properly works.

Since this is not a mainstream thing that modern EEs deal with every day, could you please post some links to basic information about these devices? And if you could post some links to info that refers to your questions and confusions, that would help us to help give you answers.