simple question on induction

[salter]

I was looking up formulas for inductance of a coil with an air core and i found this one. L=(r^2*n^2)/(9r+10l), where L is inductance, r is radius of coils, n is number of coils and l is length of coil... what is length of coil? is it total conductor in the coil?

 

 

also, i need to calculate resonance of an LC circuit. i got the formula R=1/2pi(LC)^1/2... does current or voltage affect resonance? does resistance?

Edited January 17, 2009 by salter

[tvp45]

I don't know that formula, but l is the axial length of the coil.

 

Voltage and current don't affect resonance unless the voltage is high enough to saturate the inductor core. Resistance affects the Q but not the frequency.

[chitrangda]

Net reactance at resonance will be zero.

X=Xl-Xc=0

i.e; circuit will be resistive and there will be no phase difference between voltage and current.

=> [math]\phi[/math]=0