Need help with circuit Analysis problem invovling inductor!?

Question

In this circuit, I have a 1mA source going into a 4.7kOhm resistor that is in parallel with a inductor. My objective is to determine the current and the voltage going through the inductor.

I thought about transform the circuit using Norton's equivalent to produce a 4.7V source in series with a 4.7kOhm resistor and the inductor, and in doing so I can determine the i since the inductor now acts as a short circuit with DC source. 

Is that correct? If not, how should I go about this problem?

? · Accepted Answer

You are mostly correct.  However when the source is initially turned on there will be no current in the inductor and it will rise exponentially from zero.  The time constant is L/R.

maisunmonwar · Answer

If you could include a circuit diagram, it would have been easier for us to give you some hints.

From your description, what I understand, you can not change the current source to a voltage source. To convert to voltage source the resistance must have nothing attached to it in parallel.

If it is a DC circuit, you can use voltage equation to find the voltage across the inductor. At the very beginning, t=0, inductor is open. so all the current will flow through R and giving you a voltage. Use this voltage as your initial voltage and determine for all t.

If it is an AC circuit, Ohm's law is enough.

Len · Answer

The only resistance in the inductor, in a dc circuit is the resistance of the wire. Measure that and it is in parallel with the other resistance.
In an ac circuit the resistance of the inductor will be the reactance to the ac voltage.

Reactance for an inductor. XL = 2pi times Frequency times Inductance in Henries. XL = 2Ï x fL
All reactances and resistances are measured in Ohms.

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Need help with circuit Analysis problem invovling inductor!?

3 Answers