EGR 203 Electric and Electronic Circuits Assignment 14
- The heating element in a soldering iron has a resistance of
30 Ω. Find the average power dissipated in the soldering iron
if it is connected to a voltage source of 117 V rms.
- A current of 4 A rms flows when a neon sign is supplied by a 110-V
rms power system. The current lags the voltage by 60°.
Find the power dissipated by the circuit and the power factor.
- A drilling machine is driven by a single-phase induction motor
connected to a 110-V rms supply. Suppose that the machining operation
requires 1 kW, that the tool machine ihas 90 percent efficiency, and
that the supply current is 14 A rms with a power factor of 0.8. Find
the AC machine efficiency.
- A single-phase circuit is placed across a 120-V rm, 60-Hz
source, with an ammeter, a voltmeter, and a wattmeter connected. The
instrucments indicate 12 A, 120 V, and 800 W, resppectively. Find
(a) the power factor, (b) the phase angle, (c) the impedance, and (d)
the resistance.
- For the following numeric values, determine the average power
P, the reactive power Q, and the complex power S
for the circuit below. Phasor values are rms.
- vs = 650 cos(377t) V
iL = 20 cos(377t − 10°) A
- Vs = 460Ð0° V
IL = 14.14 Ð−45°
- For the circuit above, determine the power factor for the load and
state whether it is leading or lagging for the following conditions:
- vs = 540 cos(ωt + 15°) V
iL = 20 cos(ωt + 47°) A
- vs = 155 cos(ωt − 15°) V
iL = 20 cos(ωt − 22°) A
- A single-phase motor draws 220 W at a power factor of 80
percent (lagging) when connected across a 200-V, 60-Hz source. A
capacitor is connected in parallel with the load to give a unity
power factor, as shown below. Find the required capacitance.
Maintained by John
Loomis, last updated 20 July 2012