Electrical Circuits and Machines
University of New Brunswick
Department of Electrical and Computer Engineering
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EE2683 Electric Circuits & Machines
Experiment #1: Phase relationships in A-C circuits
The purpose of this experiment is to review and reinforce your understanding of the phase
relationships in series and parallel a-c circuits. It should also enable you to get familiar with the use
of a dual beam oscilloscope and to conduct basic measurements and calculations.
The equipment required includes a Dual beam oscilloscope, an oscillator, individual R, L, C
components, and digital meters.
1. Equipment Familiarization
Familiarize yourself with the dual beam oscilloscope, including identification of the two inputs and
all adjustable settings. Start it up and get two horizontal traces.
2. Understanding the time base on the scope
a) Calculate the time period for the sweep circuit to display one cycle of a 60 Hz wave.
b) Display a 60 Hz voltage waveform on the screen. Check the calculated period, and that obtained
from oscilloscope measurement.
3. Resistance Measurement
The test circuit you will be using in this experiment is shown in Figure 1-1below. Use the digital
multi-meter as a digital ohmmeter.
a) Measure the resistance of the resistor.
b) Measure the resistance of the inductor.
c) Assume that the resistance of the capacitor is infinite.
Figure 1-1. A Simple RLC Test Circuit.
4. Reactance Calculation
Values of L and C will be provided in the lab. Calculate XL and XC at 1000 Hz.
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5. Impedance Calculation
Calculate the impedance ZR, ZL and ZC both in rectangular form and in polar form.
6. Dropping Resistors
As you know, current can be measured with an ammeter. However, current can also be found by
measuring the voltage across a known value of resistor. Of course any dropping resistor, or
measuring resistor, must be relati