circuits lab
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CircuitsLab02_Modified.docTennessee State University
College of Engineering
Department of Electrical and Computer Engineering ENGR 2001- CIRCUITS I LAB
LABORATORY EXPERIMENT 2
EXPERIMENT TWO
VOLTAGE AND CURRENT DIVISION
Reference: Alexander, Charles K. and Matthew Sadiku, Fundamentals of Electric Circuits, 6th Edition, McGraw Hill, 2017.
Objective:
The purpose of this experiment is to verify voltage division using a series resistor circuit and to verify current division by using a parallel resistor circuit. Students will gain further experience connecting the DMM to a circuit in order to measure currents and voltages.
Equipment:
· LTSpice
· Analog Discovery
· Breadboard
· Resistor (R1 = 1 k(, R2 = 10 k(, R3 = 15 k()
THEORY:
Voltage Divider Rule :- In a series circuit, the voltage across the resistive elements will divide in direct proportion to the magnitude of the resistance values. The sum of the voltage drops across the series resistors will equal the applied voltage.
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V R R R V 2 1 1 1 + =
V R R R V 2 1 2 2 + =
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Current Divider Rule :- For two parallel resistors of equal value, the current will divide equally. For parallel resistors with different values, the smaller resistor will have a greater current. The sum of the currents through both resistors will be equal to the applied current.
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2 1 i i i + = |
i R R R i 2 1 2 1 + =
i R R R i 2 1 1 2 + = |
Kirchhoff’s Voltage Law (KVL) :- KVL states that the algebraic sum of the potential rises and drops around a closed loop (or path) is zero.
Kirchhoff’s Current Law (KCL) :- KCL states that the algebraic sum of the current entering and leaving a node is zero. Hence,
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å
=
Leaving
Entering
I
I
PART 1: PRE-LAB CALCULATIONS:
1. Read the sections about voltage and current division from your textbook.
For the circuit in Figure 1, use voltage division to determine the voltage across each resistor and enter the results in Table 1
Figure 1: Voltage Division
2. For the circuit in Figure 2, use current division to determine the current through each resistor and enter the results in Table 2
Figure 2: Current Division
3. For the circuit in Figure 3, use voltage and current division to determine the voltage across each resistor and the current through each resistor and enter the results in Table 3
Figure 3: Voltage and Current Division
PART 2: LTSpice SIMULATION:
4. Build the circuits in Figures 1, 2, and 3 in LTSpice and perform “Analysis-Simulate” to find the voltages and currents. Measure the voltages across the resistors and current through the resistors (to be calculated) based on the Circuits given in Figures 1, 2 & 3 and enter the values in Tables 1, 2 & 3 respectively.
PART 3: MEASUREMENTS USING ANALOG DISCOVERY:
Part I:
1. Build the series circuit shown in Figure 1 on your breadboard.
2. Use the “wavegen” from the analog discovery to apply a 5V DC, measure the voltage across each resistor using Oscilloscope from the Analog Discovery and enter the measured values in Table 1.
Part II:
1. Build the parallel circuit shown in Figure 2 on your breadboard.
2. Use the “wavegen” from the analog discovery to apply a 5V DC, calculate the current through each individual resistors using Ohms law (i=V/R) and the resistor combination (in parallel). Enter this calculated currents as measured values in Table 2. We need to do this current calculation using Ohms Law because the analog discovery does not have option to measure currents directly from the circuit.
Part III:
1. Build the series-parallel circuit shown in Figure 3.
2. Use the “wavegen” from the analog discovery to apply a 5V DC, measure the voltage across the resistors and calculate the current through each resistor. Nter the voltage measured data in Table 3 as measured data and enter the calculated currents in the colum of measured data in Table 3.
Post-Lab Report: Must follow the guideline and the sample lab report
1) Create a table in Excel of the calculated, the LTSpice and the measured values. Perform an error analysis between all calculated and measured in your laboratory report
2) For each circuit, calculate the power dissipated in each resistor and confirm that the circuit obeys the law of conservation of energy.
i
i2
i
i1
R2
R1
+
-
V1
V2
R2
R1
V
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