EXPERIMENT 2:
SERIES AND PARALLEL CIRCUITS, VOLTAGE AND CURRENT DIVIDER
RULES, KIRCHOFF LAWS
A. PURPOSE OF THE EXPERIMENT:
To analyze and understand simple series and simple parallel resistor circuits. To understand
voltage and current divider rules. To apply Kirchoff's laws experimentally.
B. TOOLS AND MATERIALS TO BE USED:
1.DC power supply, 2. Multimeter, 3. Protoboard, 4. Various resistors, 5. Adjustable resistor
C. PRELIMINARY INFORMATION ABOUT THE EXPERIMENT:
• SIMPLE SERIES RESISTANCE CIRCUITS:
+ VR1 - + VR2 - + VRn -
TO
Figure 1. Simple Series Circuit
In the most general sense, a series circuit like Figure 1 is analyzed as follows:
-Equivalent resistance:
circuit:
- Total current flowing through the
- Currents flowing through each resistor:
- Voltages at the ends of each resistor:
-Voltage
balance:
-The power given by the source to the circuit:
Aydın. Ü., Department of Electrical and Electronics
1 Engineering
EXPERIMENT 2:
SERIES AND PARALLEL CIRCUITS, VOLTAGE AND CURRENT
DIVIDERRULES, KIRCHOFF LAWS
- Power dissipated on each resistor:
-Balance of Power:
Voltage Divider Rule:
The voltage divider rule is a simple and practical rule developed for calculating the voltages of
resistors connected in series in a circuit. Accordingly,
- Total voltage across the resistors: E
- Voltage balance:
(
- Voltage across each resistor: V
o
l
SIMPLE PARALLEL RESISTANCE CIRCUITS:
IR2 IR2 IRN
+ + +
TO VR1 VR2 VRn
- - -
Figure 2. Simple parallel circuit
In the most general sense, a parallel circuit like Figure 2 is analyzed as follows:
-Equivalent resistance:
-Total current flowing through the:
-Currents flowing through each resistor:
- Voltages at the ends of each resistor:
Aydın. Ü., Department of Electrical and Electronics
2 Engineering
-Current balance:
- The power given by the source to the circuit:
-Power dissipated through each resistor:
- Current Divider Rule:
The current divider rule is a simple and practical rule developed for calculating the currents of
resistors connected in parallel in a circuit. Accordingly;
-Total current at the ends of the resistors: I
- Current balance:
- Current flowing through each resistor:
KIRCHOFF'S LAWS:
It is one of the most fundamental laws used in circuit analysis after Ohm's law.
Kirchoff has two basic laws:
• Kirchoff Current Law (KCC):
According to Kirchoff's current law, the sum of the currents entering and exiting a node (or a closed
area) is equal to each other. (Node: The points where the ends of at least two resistors meet)
• Kirchoff Voltage Law (KVK):
According to Kirchoff's voltage law, the sum of the voltages across the elements in a closed
path is zero. For a simple circuit:
Aydın. Ü., Department of Electrical and Electronics
3 Engineering
EXPERIMENT 2:
SERIES AND PARALLEL CIRCUITS,VOLTAGE AND CURRENT DIVIDER
RULES, KIRCHOFF LAWS
D. EXPERIMENTAL STEPS:
1. Simple series circuit experiment.
Consider the circuit given below.
Figure 4. Simple series circuit consisting of three resistors.
- Calculation Step:
a) Analyze the circuit using calculations and fill in Table 1.
Voltage Current
Voltage Polarity Current Direction Power
R1
R2
R3
R4
- Measurement Step: ÿ Table 2 Flow
Voltage Flow
ÿ a) Complete Table 2 by Strength
taking measurements for each polarity direction
element in the circuit. (Note:
The power column will again
be filled with calculations.
Voltage
TO
R1
R2
R3
5 ÿn. Ü., Department of Electrical and Electronics Engineering
EXPERIMENT 2:
SERIES AND PARALLEL CIRCUITS,VOLTAGE AND CURRENT DIVIDER
RULES, KIRCHOFF LAWS
- Measurement Step:
a) Complete Table 2 by taking measurements for each element in the circuit. (Note:
The power column will again be filled with calculations.)
Table
2
Voltage Current
Voltage Polarity Current Direction Power
R1
R2
R3
R4
Aydın. Ü., Department of Electrical and Electronics
7 Engineering
EXPERIMENT 2:
SERIES AND PARALLEL CIRCUITS,VOLTAGE AND CURRENT DIVIDER
RULES, KIRCHOFF LAWS
b) Write the KVK equation for the circuit in Figure 4 (To do this, accept the source voltage as positive and
the resistance voltages as negative and add them). Show the accuracy of this equation by considering the
values inthe voltage column you measured in Table 2.
c) Considering the measurement results in Table 2, show that Ohm's law is satisfied for each resistance.
2. Simple parallel circuit experiment.
Consider the circuit given below.
Figure 5. Simple parallel circuit consisting of three resistors.
- Calculation Step:
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8 Engineering
Analyze the circuit using calculations and fill in Table 3.
Voltage Current
Voltage Polarity Current Direction Power
R1
R2
R3
R4
Table 3
Measurement Step:
a) Complete Table 4 by taking measurements of each element in the circuit. (Note:
The power column will again be filled with calculations.)
Table 4
Voltage Current
Voltage Polarity Current Direction Power
R1
R2
R3
R4
b) Compare the results in Table 3 and Table 4. If there are differences, investigate the
reason.
Aydın. Ü., Department of Electrical and Electronics
9 Engineering
EXPERIMENT 2:
SERIES AND PARALLEL CIRCUITS,VOLTAGE AND CURRENT DIVIDER
RULES, KIRCHOFF LAWS
E. POST-EXPERIMENT HOMEWORK:
1. Figure 3 shows three commonly used types of variable resistors. However, there are many
other types of variable resistors on the market. Figure 3 and other types. Do research on it.
Add at least one picture of each type and explain the areas of use. Please write.
2. Consider the five resistors placed randomly on the protoboard below. Place the wires between
these resistors in such a way that the circuit given next to the protoboard is obtained. (Draw the
wires on the protoboard with a red pencil)
3. Consider the five resistors placed randomly on the protoboard below. Place the wires between
these resistors in such a way that the circuit given next to the protoboard is obtained. (Draw the
wires on the protoboard with a red pencil)
Aydın U., Department of Electrical and Electronics Engineering
16
EXPERIMENT 2:
SERIES AND PARALLEL CIRCUITS,VOLTAGE AND CURRENT DIVIDER
RULES, KIRCHOFF LAWS
4. Carefully examine the circuit diagram below and its soldered form on the printed circuit board.
a) In accordance with the example given above, examine the printed circuit given below and draw
the circuit diagram.
b) Examine the printed circuit given below. There are a total of four series resistance circuits on this
plate. Accordingly, draw what type of circuits are between which ends.
ÿn. Ü., Department of Electrical and Electronics Engineering
17
EXPERIMENT 2:
SERIES AND PARALLEL CIRCUITS,VOLTAGE AND CURRENT DIVIDER
RULES, KIRCHOFF LAWS
5. In a series circuit consisting of five resistors, a current of 2 mA is measured on the
first resistor using an ammeter. Accordingly,
a) What is your comment about the amount of current through the fourth resistor? Why?
b) How does the value of the current flowing through the first resistor change when any
sixth resistor is added to the circuit? Why?
6. In a series circuit consisting of four resistors, how do the voltage values across the first
four resistors change when any fifth resistor is added to the circuit? Explain by
considering an example circuit?
7. There are three resistors of 1k Ω, 2.2k Ω and 3.3k Ω in a series circuit. Which resistor
has the largest voltage in this circuit? Explain.
8. Which of the following series resistor combinations will draw more power from a 100V
source? Why?
a) one 100 Ω b) two 100 Ω c) three 100 Ω
9. When an ammeter is connected to a series resistance circuit, what could be the
reason if the meter measures 0A?
10. When an ammeter is connected to a series resistance circuit, what could be the
reason if a higher current value is measured on the measuring device than it should be?
11. Examine the values measured with measuring instruments in the circuit given in the
figure below. What kind of problem is there in this circuit and how can this problem be
solved?
ÿn. Ü., Department of Electrical and Electronics Engineering
18
ÿn. Ü., Department of Electrical and Electronics Engineering
19
