# Mutual inductance in a circuit.

1. Nov 20, 2013

### anthonych414

1. The problem statement, all variables and given/known data

Derive TEC between terminals "ab".

2. Relevant equations

3. The attempt at a solution

I figured I'd add the mutual inductances to the inductors, and solve it as a normal RLC circuit, since no current is passing through the 80j coil, it's inductance wouldn't change. The 50j coil becomes an 80j coil (50j + 30j) and the 40j coil becomes a 70j coil (40j + 30j). Setting the voltage source to zero yields a thevenin resistance of -60 + 60j and KVL yields to a Thevenin voltage of 9 + 41j volts. However the answer says Rth = 60 + 60j and Vth = 9 + 51j. Can anyone help me identify where I went wrong? Thank you in advance.

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Last edited: Nov 20, 2013
2. Nov 20, 2013

### Andrew Mason

First of all you will have to explain the question. What does TEC stand for?

Where do you take into account the capacitor?

AM

3. Nov 21, 2013

### anthonych414

TEC stands for Thevenin Equivalent Circuit, and the capacitor does not undergo mutual inductance, so I use its phasor form to find the equivalent thevenin resistance like I would with a resistor.