2007-03-17 00:13:47 · 3 answers · asked by sarat 2 in Science & Mathematics ➔ Engineering
A simple inductor is easiest to picture; a single coil of wire.
Input current in an inductor produces a magnetic field around each section of the wire. This magnetic field induces a voltage in neighboring wraps of the inductor. The voltage induces currents which tend to oppose the the input current. Changes in the time value of the input current will create a "resistance (impedance)" to the input current.
When DC is first applied at the input, there is a step change of current and the inductor will resist the current until, afterwards, a steady state value of current is reached.
If you disconnect the DC current source from the input of the inductor, a very high voltage is induced across the inductor. That is why snubber circuits are used; to reduce this voltage spike.
When AC is first applied at the input, the change of current is always present. The inductor will resist the flow of the input current.
2007-03-17 00:25:24 · answer #1 · answered by cfpops 5 · 0⤊ 0⤋
An inductor blocks AC while allowing DC because it resists a change in current. The equation of an inductor is ...
di/dt = V/L
... meaning that the rate of change of current is proportional to voltage and inversely proportional to inductance.
If you apply DC across an inductor, it will stabilize to some current flow based on the maximum current available from the current / voltage source. In this mode, the inductor presents very low resistance, so it can be said that it allows DC to pass.
If, however, you apply AC across an inductor, you need to consider its inductive reactance by integrating the above equation in terms of the circuit conditions. The equation for inductive reactance is ...
XL = 2 pi F L
... meaning that the inductive reactance is proportional to the frequency and to the inductance.
Thus, the higher the frequency, the higher the reactance. Since reactance is a phasor measure of resistance, it can be thus said that an inductor will block AC.
https://www.electrikals.com
2015-09-28 18:11:13 · answer #2 · answered by Robert 4 · 0⤊ 0⤋
Inductors allow d/c and resist a/c.
A capacitor passes a/c and blocks d/c
2007-03-17 00:19:25 · answer #3 · answered by Billy Butthead 7 · 0⤊ 0⤋