Mutual inductance in a circuit.

[anthonych414]

Homework Statement

Derive TEC between terminals "ab".

Homework Equations

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.

 

[Andrew Mason]

Homework Statement

Derive TEC between terminals "ab".

Homework Equations

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.

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

Where do you take into account the capacitor?

AM

 

[anthonych414]

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

Where do you take into account the capacitor?

AM

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.