Inductor equations

If we assume that a constant DC current has been flowing through the inductor for some time, then \frac{dI_{L}}{dt} is zero and thus V_{L} is zero.

Under DC conditions the inductor acts like a short circuit.

Inductive reactance is measured in Ohms and it tells as “how bad” the inductor passes the current.

Inductive susceptance is measured in Siemens and it tells as “how well” the inductor passes the current.

Practical inductor, RL in series:

Q=2 \pi \frac{maximum \ energy \ stored}{energy \ dissipated \ per \ cycle}=2 \pi \frac{\frac{1}{2}LI_{max}^2}{(\frac{I_{max}}{\sqrt{2}})^2RT}=2 \pi \frac{L}{R \frac{1}{f}}=\frac{2 \pi f L}{R}=\frac{X_{L}}{R}