# Worksheet: Impedance and Power of Alternating-Current Circuits

In this worksheet, we will practice calculating the impedance of RLC alternating current circuits and how phase angle depends on impedance and frequency.

**Q2: **

A 20 ฮฉ resistor, 50 ยตF capacitor, and 30 mH inductor are connected in series with an ac source of amplitude 10 V and frequency 125 Hz.

What is the impedance of the circuit?

What is the amplitude of the current in the circuit?

What is the phase constant of the current?

How much energy is dissipated by the resistor in 2.5 s?

**Q6: **

An RLC series circuit consists of a 50 ฮฉ resistor, a 200 ยตF capacitor, and a 120 mH inductor whose coil has a resistance of 20 ฮฉ. The source for the circuit has an rms emf of 240 V at a frequency of 60 Hz.

Calculate the rms voltage across the resistor.

Calculate the rms voltage across the capacitor.

Calculate the rms voltage across the inductor.

**Q9: **

An RLC circuit includes a resistor of resistance 0.50 kฮฉ and an inductor of inductance 0.20 H. The circuit is connected to a 100 V, 0.50 kHz source.

Find the average power dissipated in the resistor if the capacitance of the circuit is 2.0 ยตF.

Find the average power dissipated in the resistor if the capacitance of the circuit is 0.20 ยตF.