Question

PROBLEM 4.3
A coil connects to a 120 volt, 50 hertz alternating voltage source; as it's shown in the following. Obtaining the following readings:
Wattmeter reading = 15 watts
Ammeter Reading = 7.5 Amps
A) Calculate the effective resistance when the coil has a rolled steel core, if it has a power consumption of 20 watts and a current of 6 amps
B) Calculate the effective resistance when the coil has a solid cast iron core, and dissipates a power of 60 watts and a current of 6 amps.

120 V

Answer 1

iven wattmeter reading : 15 watts . Ammeter reading = 7.5A 1 wa v. I cose - =cosd : 0.0167, 15 . 77.5)(120) - Vreading : 120v wattmeter reading : ao watts Anmeter reading : 6 Amps (I?) Refp = Wattmeter reading 162 Reff = 20 Reff = 20/36 = 0.562 : 120 V . . 3) Vaeading : 60 watts = 6 Amps wattmeter reading Ammeter reading - CLIŽ Reff = 60 Reff: 60/36 = 1.672