Why current lags behind voltage, but frequency of both remains same in case of inuctive circuit?

Answer 1

Draw a sine wave: this represents the variation of current with time. A voltage is induced by changing current: so at the start of the sine wave the voltage will be maximum because the curve is steepest. Now as the current increases to maximum its rate of change decreases (the curve gets less steep) so the induced voltage also decreases. When the current is maximum, its rate of change is zero: so the induced voltage is zero So in the first quarter cycle, when the current goes from zero to maximum, the voltage goes from maximum to zero. Continue with this, sketching a graph for voltage against time underneath the one for current against time. So when the current is decreasing most rapidly the voltage will be negative and of maximum magnitude. When you have done this for one complete cycle you will see that the current curve lags behind the voltage curve by one quarter of a cycle but, since there is just one cycle for current and one cycle for voltage, the frequencies are the same.

Answer 2

Inductive reactance (symbol X L) is caused by the fact that a current is accompanied by a magnetic field; therefore a varying current is accompanied by a varying magnetic field; the latter gives an electromotive force that resists the changes in current.
The more the current changes, the more an inductor resists it: the reactance is proportional to the frequency (hence zero for DC).
There is also a phase difference between the current and the applied voltage.

Inductive reactance has the formula

Inductive Reactance , X L = ωL = 2π f L
where

XL is the inductive reactance, measured in ohms
ω is the angular frequency, measured in radians per second
f is the frequency, measured in hertz
L is the inductance, measured in henries

There is a similar phenomenon in a Capacitive Recatance circuit

And of course the two combine to form tuned circuits


Remember C I V I L ?..

Answer 3

In an AC circuit, the alternating currents create an electro magnetic field upon itself. Since the electromagnetic field also induces an electromotive force, this force reacts on the impressed electron flow in an opposite direction at the same time. The resultant combination of electron flow in one direction with an opposite electron flow causes opposition to the total flow of current. Remember that when no current flows as when the circuit is off, there is no electromagnetic field. It takes current flowing in a direction to have an electromagnetic field. No current flow, no electromagnetic field. At this time the current and voltage must be in complete phase with each other. Transformers used to reduce or increase the voltage electrically cause inductance and its resultant is inductive reactance. Inductive reactance is opposite of capacitive reactance and is measured in ohms like resistance.

Answer 4

Inductors oppose changes in current, and in trying to oppose current, they induce voltages across them for a period of time, based on voltage applied and the size of the inductor. Once the transient has died, the inductor will pass current.

So procedurally the inductor sees voltage before it sees current.

Answer 5

voltage induces current, so it happens later