Adnan Menderes University
Elec. & Electronics Eng. Dept.
EE209 Circuit Laboratory I
2015-2016
1.1 Objectives
In this experiment, you will learn:
1.
what the resistance concept is and what the related constant and variable resistors are
2.
how to read the color codes of resistors to determine the manufacturer’s resistance values.
3.
how to use a multimeter for resistance measurements.
4.
how to measure the AC line voltage.
5.
how to measure DC currents and voltages with a digital multimeter in a resistive circuit.
6.
how the voltage and current dividers operate for resistive loads.
1.2 Equipment List
1. Power Supply
2. Digital multimeter
3. Breadboard
4. Carbon resistors: 1.5 kΩ, 4.7 kΩ, 10 kΩ , 18 kΩ, 100 kΩ
6. Potentiometers: 1 kΩ POT, 10 kΩ POT
1.3 Preliminary Work
1.
From the textbook of the Circuit Theory course or internet sources, review the following concepts: a.
Concept of electrical resistance, type of constant and variable resistors and color codes b.
Circuit analysis methods c.
Notes on and how to measure current, voltage and resistance
2.
Find the voltage, current and power values for the circuit given in Figure 1.2 theoretically and record that values into Table 1.4 (Calculated Values (theoretical)) (Hint : Use Ohm’s and
Kirchhoff’s Laws)
3.
Find the current values ( i ) for the circuit given in Figure 1.3 when v’ is tuned as 0, 2, 4, 6, 8, and
10 volts theoretically and record that values into Table 1.5 ( i (mA) (calculated) ) (Hint : Use
Ohm’s Law)
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1.4 Experimental Work
1.
In this step, you will investigate the reading of resistors using resistor color codes. Moreover you will measure resistance value of a resistor by using digital multimeter. a) Read the color codes and determine the nominal value and tolerance of any three of carbon resistors and record them in Table 1.1. b) Measure the values of the resistors (which are used in part a) with the digital multimeter and record them in Table 1.1.
Table 1.1
Resistor Color1 Color 2 Color 3 Color 4
R
1
R
2
R
3
Calculated Resistance value (from color codes)
Measured
Resistance value
2.
In this part of experiment, we will be investigating the properties of the potentiometers (POT).
The potentiometer is a variable resistor.
Inner structure of potentiometers can be seen in
Figure 1. By rotating the shaft (slider), you can change the resistor values in between the terminals 1 and 2, and terminals 2 and 3 separately.
Figure1.1
Inner structure of a Potentiometer and a typical Potentiometer. a) For 1 kΩ and the 10 kΩ POTs measure the resistor values between the terminals 1 and 2 to find their minimum and maximum resistance values by using the digital multimeter and record them in Table 1.2.
R
1-2
(1 kΩ POT)
Table 1.2
R
2-3
(1 kΩ POT)
R
1-2
(10 kΩ POT)
R
2-3
(10 kΩ POT)
R min
R max
2

b) Rotate the shaft (slider) of Potentiometers anywhere randomly and measure the resistance values by using the digital multimeter and record them in Table 1.3.
1 kΩ POT
10 kΩ POT
R
1-2
R
2-3
Table 1.3
R
1-3
R
1-2
R
2-3
R
1-3
3.
Set the digital multimeter to AC voltage measurement and measure the line voltage. Be sure that the multimeter must be in the 750 V AC scale and be sure that “AC” and “V” symbols are appeared on the screen of multimeter. After this setup, call your instructor and measure the line voltage with the assistance of him/her. Write the measured value below.
Line Voltage =…………..
4.
Adjust the DC power supply to output 12V and s et up the circuit in Figure 1.2. Measure and record all the currents and the voltages regarding to each resistor by using the digital multimeter.
Calculate the power dissipated in each resistor by P = i.v. Find them also by your own calculations by applying any method you know from your circuit theory courses and fill in Table
1.4. Are the measured and calculated values in agreement? If there are small differences, explain its reasons.
Figure 1.2
Diagram of the circuit in Part 4.
Measured Values (experimental)
Calculated Values (theoretical)
Table 1.4
i
1 i
2 i
3 v
1 v
2 v
3
P
1
=i
1
.v
1
P
2
=i
2
.v
2
P
3
=i
3
. v
3
3

5. Setup the circuit in Figure 1.3. Use 1 kΩ POT as R
1
and 4.7 kΩ resistor as R
2
. Then vary the position of the potentiometer so that v’ is 0, 2, 4, 6, 8, and 10 volts. For each case measure current i and record it in
Table 1.5.
Figure 1.3
Diagram of the circuit in Part 5.
Table 1.5 (for R
2
=4.7
kΩ) v’
=0 V v’
=2 V v’
=4 V v’
=6 V v’
=8 V v’
=10 V i (mA) (measured) i (mA) (calculated) a) Plot i vs. v graph and determine the resistance of R
2
by using i vs. v graph . (“ i ” must be placed in yaxis and “ v ” must be placed in x-axis) (Hint: What is the slope of i vs. v curve?) b) Measure and record the resistance of R
2 by using the digital multimeter. c) Compare the results obtained in Parts 6.a and 6.b. Do they match? If there is a small difference, explain its reasons.
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