International Islamic University Chittagong Department of Electrical & Electronics Engineering

International Islamic University Chittagong Department of Electrical & Electronics Engineering Course No: EEE 1102 Course Title: Electrical Circuit I Sessional Experiment No : 01 Experiment Name: Introduction to a Multimeter. Objective: The objective of the experiment is to be familiar with using of Multimeter as a Voltmeter, an Ammeter and an Ohmmeter. Theory: Multimeters are designed and mass produced. The simplest and cheapest types may include features which are not likely to use. A multimeter or a multitester is an electronic measuring instrument that combines several functions in one unit. The most basic instruments include an ammeter, voltmeter, and ohmmeter. Analog multimeters are sometimes referred to as "volt-ohm-meters", abbreviated VOM. Digital multimeters are usually referred to as "digitalmulti-meters", abbreviated DMM A meter is a measuring instrument. An ammeter measures current, a voltmeter measures the potential difference and an ohmmeter measures the resistance. A multimeter combines all these functions and possibly some additional ones as well, into a single instrument. Digital meters give an output in numbers, usually on a liquid crystal display. There are two or more probes with a multimeter; one of which is black to be placed in common and other one is red which needs to be placed according to the quantity to be measured. Circuit Diagram: Apparatus: 1. Multimeter 2. Resistor 3. Project Board 4. Voltage Source Page 1 of 21

Observation: Measure the voltage drops; V1 V2, across the resistors R1 and R2. And measure the current through the resistor/s. Precautions for Voltage Measurements Plug the black test lead into the COM jack. Plug the red test lead into the V jack. Set the function/range switch to either o DC volts in the upper left, or o AC volts in the upper right. If you do not know the approximate voltage about to be measured, use the largest voltage range available. Connect the free ends of the red and black test leads ACROSS the device to the measured. Voltage is always measured with the meter in PARALLEL with the device. If the LCD displays either "1." or "-1." with all other digits blank, the voltage is beyond the selected range. Use the switch to select a larger range. Once you know the approximate voltage across the device, then use the switch to select the lowest voltage range that will still accommodate the voltage across the device. Precautions for Current Measurements Turn the power off to the device and discharge any capacitors! Plug the black test lead into the COM jack. Plug the red test lead into either the o 200 ma jack for small current measurements, or the o 10 A jack for large current measurements. If you do not know the approximate current about to be measured, use the 10 A jack. Set the function/range switch to either o DC amperes in the lower right, or o AC amperes in the middle right. Break open the circuit at the point where you want to measure the current by removing one of the wires. Connect the free end of the red test lead to one place at which the wire was attached. Connect the free end of the black test lead to the other place at which the wire was attached. Current is always measured with the meter in SERIES with the device. If you do not understand the difference between SERIES and PARALLEL, ask your TA. Using the current meter incorrectly will blow the fuse or damage the meter. (It will also cost you points on your lab write up.) Reapply the power to the device. If the LCD displays either "1." or "-1." with all other digits blank, the current is beyond the selected range. Use the switch to select a larger range. Once you know the approximate current through the device, then use the switch to select the lowest current range that will still accommodate the current through the device. Turn the power off to the device before removing the meter from the circuit. Page 2 of 21

Precautions for Resistance Measurements Turn the power off to the device and discharge any capacitors! Plug the black test lead into the COM jack. Plug the red test lead into the VΩ jack. Set the function/range switch to ohms (Ω) in the lower left. If you do not know the approximate resistance about to be measured, use the largest range available. Connect the free ends of the red and black test leads ACROSS the device to the measured. Resistance is always measured with the meter in PARALLEL with the device. If the LCD displays either "1." or "-1." with all other digits blank, the resistance is beyond the selected range. Use the switch to select a larger range. Once you know the approximate resistance of the device, then use the switch to select the lowest range that will still accommodate the resistance of the device. Page 3 of 21

International Islamic University Chittagong Department of Electrical & Electronics Engineering Course No: EEE 1102 Course Title: Electrical Circuit I Sessional Experiment No: 02 Experiment Name: Color Code of Resistor. Objective: The objective of the experiment is to the resistance of a resistor from its color code. Theory: The resistor color code is a long standing standard in both the electronics and electrical industries, indicating the value of resistance of a resistor. Resistance is measured in ohms and there is a foundation for it called Ohm's Law. Each color band represents a number and the order of the color band will represent a number value. The first 2 color bands indicate a number. The 3rd color band indicates the multiplier or in other words the number of zeros. The fourth band indicates the tolerance of the resistor +/- 20%, 10% or 5%. In most cases, there are 4 color bands. However, certain precision resistors have 5 bands or have the values written on them, refining the tolerance value even more. The electronic color code was developed in the early 1920s by the Radio Manufacturer's Association, now part of Electronic Industries Alliance and was published as EIA-RS- 279. The current international standard is IEC 60062. Advantages of color coding (over printed text) on physically small components are the inherent increase in marking area, which makes the values easier to read without magnification, and a 360 degree viewing angle which cannot be achieved with text. Color coded markings are also more resistant to abrasion. Color 1st Band 2nd Band 3rd Band (Multiplier) 4th Band (tolerance) Black 0 0 10 0 Brown 1 1 10 1 ±1% Red 2 2 10 2 ±2% Orange 3 3 10 3 Yellow 4 4 10 4 Green 5 5 10 5 Blue 6 6 10 6 Violet 7 7 10 7 Gray 8 8 10 8 White 9 9 10 9 None ±20% Silver 0.01 ±10% Gold 0.1 ±5% Page 4 of 21

Apparatus: 1. Multimeter 2. Resistors 3. Calculator Observation: Measure the resistance of the resistors given from the color code and also with the help of multimeter. No 1st Band 2nd Band 3rd Band 4th Band Calculated Resistance Measured(From Multimeter) Page 5 of 21

International Islamic University Chittagong Department of Electrical & Electronics Engineering Course No: EEE 1102 Course Title: Electrical Circuit I Sessional Experiment No : 03 Name of the Experiment: Verification of Ohm s Law Objective: To establish the voltage-current relationship in an electrical circuit Theory: Ohm's law states that, in an electrical circuit, the current passing through a conductor between two points is proportional to the potential difference (i.e. voltage drop or voltage) across the two points, and inversely proportional to the resistance between them. In mathematical terms, this is written as: where I is the current in amperes, V is the potential difference in volts, and R is a constant, measured in ohms, called the resistance. The potential difference is also known as the voltage drop. Circuit Diagram: Apparatus: 1. Multimeter 2. DC voltage source 3. Resistors 1k-2, 2k-1, 3k-1, 4k-1, 5k-1 4. Project board Page 6 of 21

Procedure: 1. Make the circuit diagram as shown. 2. Keep the resistor R2 1k and R1 1k. 3. Take the reading of voltage across the R2 and Current through R2. 4. Change the value of R1 to 2k, 3k, 4k and 5k take the readings of voltage and current every time. 5. Plot the values of voltage and current and verify ohm s law. Observation: Voltage, V(V) Current, I (A) Report: Draw the voltage-current relationship. Page 7 of 21

International Islamic University Chittagong Department of Electrical & Electronics Engineering Course No: EEE 1102 Course Title: Electrical Circuit I Sessional Experiment No : 04 Name of the Experiment: Verification of Kirchhoff s Current Law Objective: To verify Kirchhoff s Current Law (KCL) using nodal analysis of the given circuit. Theory: Kirchhoff s Current Law states that the algebraic sum of all the currents meeting at any node (junction) is zero. In another way KCL implies that the total currents entering a node is equal to the total currents leaving the node. Applying Kirchhoff s current law to the first four nodes in the circuit shown in Figure1 yields the following equations; Node a: -Is + I1 = 0 (2a) Node b: -I1 + I2 + I3 = 0 (2b) Node c: -I3 + I4 = 0 (2c) Node d: -I2 - I4 + I5 = 0 (2d) Apparatus: 1. Resistors (5) 2. DC source 3. Multimeter 4. Bread Board Page 8 of 21

Procedure: 1. Construct the circuit in bread board as shown in the figure 1. R 1 = 1kΩ R 2 = 2.4kΩ R 3 = 1.2kΩ R 4 = 1kΩ R 5 = 1kΩ 2. Set the dc power supply at 5 volts. 3. Measure the currents I S, I 1, I 2, I 3, I 4 and I 5 through the branches as shown in the figure with the help of the multimeter. Observation: Verify the equations 2a, 2b, 2c and 2d with the measured values of currents. Reports: 1. Theoretically calculate the currents for each element in the circuit and compare them to the measured values. 2. Compute the percentage error in the two measurements and provide a brief explanation for the error. Page 9 of 21

International Islamic University Chittagong Department of Electrical & Electronics Engineering Course No: EEE 1102 Course Title: Electrical Circuit I Sessional Experiment No : 05 Name of the Experiment: Verification of Kirchhoff s Voltage Law Objective: To verify Kirchhoff s Voltage Law (KVL) using mesh analysis of the given circuit. Theory: Kirchhoff s Voltage Law states that the algebraic sum of all the voltages around any closed path (loop or mesh) is zero. In other way the sum of the voltage drops around a closed path or loop is equal to the sum of the voltage rises around that path. Applying Kirchhoff s voltage law to the first and the second loops in the circuit shown in Figure 1 yields: Loop 1: -Vs +V1 +V2 +V5 = 0 (1a) Loop 2: -V2 +V3 +V4 = 0 (1b) Apparatus: 1. Resistors (5) 2. DC source 3. Multimeter 4. Bread Board Procedure: 1. Construct the circuit in bread board as shown in the figure 1. R 1 = 1.2kΩ, R 2 = 3kΩ, R 3 = 1kΩ, R 4 = 3kΩ, R 5 = 5.6kΩ 2. Set the dc power supply at 5 volts. 3. Measure the voltages cross the resistors and note down the data in the table. Page 10 of 21

4. Measure the total current. 5. Change the source voltage to 10 volts and repeat the instructions 2 to 4. Observation: No. of observation Source voltage(v) Voltage across (V) R 1 R 2 R 3 R 4 R 5 Total current(a) Calculation: Verify whether your data agree with KVL. Reports: 1. Theoretically calculate the voltages for each element in the circuit and compare them to the measured values. 2. Compute the percentage error in the two measurements and provide a brief explanation for the error. Page 11 of 21

International Islamic University Chittagong Department of Electrical & Electronics Engineering Course No: EEE 1102 Course Title: Electrical Circuit I Sessional Experiment No : 06 Name of the Experiment: Study of Voltage and Current Divider Rule. Objective: To verify the voltage and current division properties. Theory: Voltage and Current division allow us to simplify the task of analyzing a circuit. Voltage Division allows us to calculate what fraction of the total voltage across a series string of resistors is dropped across any one resistor. For the circuit of Figure 1, Voltage Division formulas are: Figure 1. Voltage Divider Current Division allows us to calculate what fraction of the total current into a parallel string of resistors flows through any one of the resistors. For the circuit of Figure 2. Current Division formulas are: Page 12 of 21

Figure 2. Current Divider. Apparatus: 1. Resistors 2. Bread Board 3. DC power supply 4. Multimeter Procedure: 1. Verifying the voltage division: a) Construct the circuit as shown in Figure 1. Measure the voltages v1 and v2 by choosing R1 =5.6 KΩ, R2 = 1.2 KΩ and setting the variable power supply voltage Vs = 5V. Repeat this step for R1 = R2 = 5.6 KΩ and note down the measurements. b) Calculate the voltages v1 and v2 by using the formulas (1) and (2) in each case. c) Compare the results from steps 1a and 1b. d) Repeat all previous steps using voltage source Vs= 10 V. 2. Verifying the current division: a) Construct the circuit as shown in figure 2. Measure the currents I s, I 1 and I 2 by choosing R1 = 2.4 KΩ, R2 = 5.6 KΩ and Rs = 1 KΩ. Set the variable power supply voltage Vs = 10 V. Repeat this step by using R1 = R2 = 2.4 KΩ and note down the measurements. b) Calculate the currents I1 and I2 by using the formulas (3) and (4). c) Compare the results from steps 2a and 2b. d) Repeat all steps using voltage source Vs= 10 V. Observation: For voltage division rule: Obs. No. Vs (V) Total Current I (ma) R1 (Ω) R2 (Ω) V1 (V) V2 (V) V1 +V2 (V) Mean (V1+V2) (V) Page 13 of 21

For current division rule: Obs. No. Total Current I (A) Source Voltage Vs (V) R1 (Ω) R2 (Ω) I1 (ma) I2 (ma) I1 + I2 (ma) Mean(I1+ I2) (ma) Report: 1. How well did the measured outputs and calculated outputs compare? Explain any difference. 2. Can you apply current division to obtain I1 and I2 for the circuit shown in the figure below? Explain briefly. Figure 3. Page 14 of 21

International Islamic University Chittagong Department of Electrical & Electronics Engineering Course No: EEE 1102 Course Title: Electrical Circuit I Sessional. Experiment No : 07 Name of the Experiment: Study of Super Position Theorem in Circuit Analysis. Objective: To understand and study the superposition theorem. Theory: Superposition Theorem states that the response in a linear circuit with multiple sources can be obtained by adding the individual responses caused by the separate independent sources acting alone. For an independent source acting alone, all other independent voltage sources are replaced by short circuits and all other independent current sources are replaced by open circuits. Figure 1 Figure 2 Figure 3 Page 15 of 21

Apparatus: 1. Resistors (3) 2. Bread Board 3. Multimeter 4. DC power supply Procedure: Verifying the superposition theorem: a) Construct the circuit of Figure 2. Measure and record the voltage across the 3.3 KΩ resistor. b) Construct the circuit of Figure 3. Measure and record the voltage across the 3.3 KΩ resistor. c) Calculate the total response Vout for circuit of Figure 3 by adding the responses from steps a and b. d) Record the voltage Vout applying both sources at a time. Report: For each of the three circuits you built for the superposition experiment, how well did the calculated and measured outputs compare? Explain any differences. Page 16 of 21

International Islamic University Chittagong Department of Electrical & Electronics Engineering Course No: EEE 1102 Course Title: Electrical Circuit I Sessional. Experiment No : 08 Name of the Experiment: Study of Thevenin s Theorem in Circuit Analysis. Objective:To verify Thevenin s theorem by obtaining the Thevenin equivalent voltage (V TH ) and Thevenin equivalent resistance (R TH ) for the given circuit. Theory: Thévenin s Theorem is a process by which a complex circuit is reduced to an equivalent series circuit consisting of a single voltage source (V TH ), a series resistance (R TH ) and a load resistance (R L ). After creating the Thévenin Equivalent Circuit, the load voltage (V L ) or the load current ( I L ) may be easily determined. One of the main uses of Thévenin s theorem is the replacement of a large part of a circuit, often a complicated and uninteresting part, by a very simple equivalent. The new simpler circuit enables us to make rapid calculations of the voltage, current, and power which the original circuit is able to deliver to a load. It also helps us to choose the best value of this load resistance for maximum power transfer. Page 17 of 21

Procedure: Verifying the Thévenin s theorem: a) Construct the circuit of Figure 1 using the following component values: R 1 = 300 Ω R 2 = 560 Ω R 3 = 560 Ω R 4 = 300 Ω R 5 = 820 Ω R L = 1.2 kω V S = 10 V b) Accurately measure the voltage V L across the load resistance. c) Find V TH : Remove the load resistance R L and measure the open circuit voltage Voc across the terminals. This is equal to V TH. d) Find R TH : Remove the source voltage VS and replace it with a short circuit. Measure the resistance looking into the opening where R L was with an ohmmeter (DMM). This gives R TH. e) Obtaining V TH and R TH, construct the circuit of figure 2. Set the value of R TH using a Decade Resistance Box. f) Measure the V L for this circuit and compare it to the V L obtained from circuit of figure 1. This verifies the Thévenin theorem. g) Repeat steps 1(b) to 1(f) for R L = 3.3 kω. Page 18 of 21

International Islamic University Chittagong Department of Electrical & Electronics Engineering Course No: EEE 1102 Course Title: Electrical Circuit I Sessional. Experiment No : 09 Name of the Experiment: Study of Millman s Theorem in Circuit Analysis. Objective:To verify Millman s theorem by reducing any number of parallel voltage sources into one voltage source(e eq ) and any number of parallel resistances into one resistance (R eq ) for the given circuit. Theory: Through the application of Millman s theorem, any number of parallel voltage sources can be reduced to one. This would permit finding the current through or voltage across R L without having to apply a method such as mesh analysis, nodal analysis, superposition, and so on. Procedure: Verifying the Millman s theorem: a) Construct the circuit of Figure-1 using the following component values: R 1 = 100 Ω R 2 = 500 Ω Page 19 of 21

R 3 = 300 Ω R L = 1kΩ E 1 = 10 V E 2 = 5V E 3 = 8 V b) Accurately measure the voltage V L across the load resistance. c) Find E eq : Remove the load resistance R L and measure the open circuit voltage Voc across the terminals. This is equal to E eq. d) Find R eq : Remove the parallel voltage sources E 1, E 2 and E 3 and replace it with a short circuit. Measure the resistance looking into the opening where R L was with an ohmmeter (DMM). This gives R eq. e) Obtaining E eq and R eq, construct the circuit of figure-2. Set the value of R eq using a Decade Resistance Box. f) Measure the V L for this circuit and compare it to the V L obtained from circuit of figure-1. This verifies the Millman s theorem. Theoretically: (a) Find E eq and R eq by using the following equations: (b) Measure I L using ohms s law i.e. I L= E eq /( R L+ R eq ). (c) Find V L using V L= I L R L. (d) Now find the percentage error using practical and theoretical result. Report: Use the mesh analysis to find the current I L,hence V L and compare the result with Millman s theorem. Engr. Sk. Md. Golam Mostafa Assistant Professor,EEE International Islamic University Chittagong(IIUC) Page 20 of 21