1,3,5 and 7

1. Consider a square wave of frequency f and peak voltage Vm, such as shown in Figure 2.1(b). Compute the RMS voltage V. 2.22. PROBLEMS 2-21 2. Consider a triangle wave of frequency f and peak voltage Vm, such as shown in Figure 2.1(c). Compute the RMS voltage V. 3. Consider a sawtooth wave of frequency f and peak voltage Vm, such as shown in Figure 2.1(d). Compute the RMS voltage V. 4. The El Paso Electric Company owns a 345kV transmission line connecting the Newman power plant in northeast El Paso to the Arroyo substation in Las Cruces, New Mexico, a distance of approximately 30 miles. At the substation, step-down transformers convert 345kVAC to 115kV and 69 kV. Power from the substation is eventually stepped down to 120V for residential customers. Compute the relative power losses if the 345kV transmission lines were instead operated at (a) 115kV; (b) 69kV; or (c) 120V. 5. An incandescent lightbulb consumes 100W at 120V. What is the current and resistance of the light? 6. A single-phase motor is supplied 7A at 220V. Compute the motor's power output (in watts and horsepower) if its efficiency is 80% and its power factor is 70%. 7. A three-phase motor is supplied 7A at 220V. Compute the motor's power output (in watts and horsepower) if its efficiency is 80% and its power factor is 70%