Hi
Electric current through a DC RL circuit ("R" stands for resistor and "L" stands for inductor) reaches its maximum value after 5τ (where "τ" is RL time constant and equals L/R). For example, in
this RL circuit, when switch is closed, momentarily equal and opposite voltage appears across the inductor which 'pushes' back the pressure exerted by the battery and therefore current is zero. But then the voltage across the inductor starts dying away and current starts increasing. If you an ammeter connected in series in the circuit and a voltmeter connected parallel with the inductor, their readings will reflect this. After 5τ, voltage appearing across the inductor is 0 and current through it is maximum.
But I'm having difficulty conceptualizing the phenomenon when you replace DC with an AC source to create AC RL circuit such as
**broken link removed** one.
Here is what I think. The voltage of an AC source is continuously changing values. For example, when voltage starts rising from 0 towards positive peak value, how would inductor behave? In my opinion as the AC voltage builds up (going from 0 towards +ve peak value), so does the voltage appearing across the inductor but this voltage should equalize (which means it cancels the pressure pressure exerted by the AC source) the voltage of the source. But this would mean that there won't be any current in the circuit as voltage goes from 0 towards the positive peak value because the voltage appearing across the inductor is opposite and equal. But once the voltage of AC source has reached the positive peak, it will start declining toward 0. Then, what?!
Please help me. Thanks.
Regards
PG