2/15/2014
Inductors
Peter Mathys
ECEN 1400
Inductors
• An inductor is a passive element that can store
energy in its magnetic field.
• Two examples: Solenoidal (left) and toroidal
(right) 100 μH inductors.
1
2/15/2014
i-v Relationship for L
• Inductance L is measured in henry (H). Typical
values range from μH (10-6 H) to about 1 H.
Inductance of Solenoid L
• Single layer of N turns of wire on core material
with permeability μ. Length l (ell) and crosssection A.
2
2/15/2014
Power and Energy
• Inductor does not dissipate power.
• Inductor can store energy => has memory.
Inductors in Series
3
2/15/2014
Inductors in Parallel
L and Sinusoidal Signals
• Since vL(t) = L·diL(t)/dt, inductors are short
circuits for dc => Cannot measure i-v
characteristic using dc signals.
• Try setting iL(t) = IA·cos(ωt) where IA is the
amplitude of iL(t) and ω=2πf is the frequency
in radians/sec (f is frequency in Hz or sec-1).
• Then observe vL(t) for different values of IA
and ω (or f).
4
2/15/2014
Inductors and Sinusoids
Graphically
5
2/15/2014
Compare to Capacitor
Using Complex Numbers
6
2/15/2014
Impedance of L
Series R,L,C Circuit
7
2/15/2014
Parallel R,L,C Circuit
8