394 Chapter 7 AC Power HOMEWORK PROBLEMS Section 7.1: Power in AC Circuits 7.1 The heating element in a soldering iron has a resistance of 30 2. Find the average power dissipated in the soldering iron...

Question 7.3

Extracted text: 394 Chapter 7 AC Power HOMEWORK PROBLEMS Section 7.1: Power in AC Circuits 7.1 The heating element in a soldering iron has a resistance of 30 2. Find the average power dissipated in the soldering iron if it is connected to a voltage source of 117 V rms. 7.2 A coffeemaker has a rated power of 1,000 W at 240 V ms. Find the resistance of the heating element. 7.3 A current source i (t) is connected to a 50-2 resistor. Find the average power delivered to the resistor, given that i (t) is a. 5 cos 50t A b. 5 cos(50t - 45°) A c. 5 cos 50t - 2 cos(50t - 0.873) A d. 5 cos 50t -2 A 7.4 Find the rms value of each of the following periodic currents: a. cos 450t +2 cos 450t b. cos 5t + sin 5t c. cos 450t + 2 d. cos 5t + cos(5t +/3) e. cos 200t + cos 400t 7.5 A current of 4 A flows when a neon light advertisement is supplied by a 110-V ms power system. The current lags the voltage by 60°. Find the power dissipated by the circuit and the power factor. 7.6 A residential electric power monitoring system rated for 120-V rms, 60-Hz source registers power consumption of 1.2 kW, with a power factor of 0.8. Find a. The ms current. b. The phase angle. c. The system impedance. d. The system resistance.