Tutorial 12 A Self Test 
1. Complete these sentences. A perfect inductor has ________________ resistance, but real inductors have a resistance.
We model this as a ____________ _____________ in _____________ with a resistor.
As the frequency increases, the ____________________ of the inductor increases.
The voltage across the resistor is ___ _______________ with the current. The current in the inductor leads/lags the voltage by __________ degrees.
2. Draw a phasor diagram to show the phase relationships between the voltage and the currents in a parallel RL circuit that has a perfect inductor. 3. A student works out the impedance of a parallel RL circuit using the equation:
Discuss whether this is correct.
4. Starting from the vector addition of currents in a parallel RL circuit, derive an equation for the impedance of the circuit.
5. Calculate the overall impedance of this circuit, if the frequency is 20 Hz.
