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The details of various experiments aimed at verifying electrical theorems such as Kirchhoff's Laws, Thevenin's Theorem, and Superposition Theorem. Additionally, it covers the study and testing of electronic components, including identification of their terminals, and the discussion of resistors, inductors, capacitors, diodes, and transistors.
Typology: Slides
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Aim: Verification of Kirchhoff‟s Laws
Objective: i. To measure voltage and current in a DC circuit for each element, ii. to calculate analytically V & I iii. compare analytical and practical values iv. verify KVL & KCL.
Requirements:
Sr. No. Equipment / Instrument Device Rating/Value Quantity 1 Resistance 460 Ω, 720 Ω, 330 Ω, 680 Ω, 220 Ω
each 01
2 Current meter (DC) (Multimeter)
0 - 1 A at least 02
3 Volt meter (Multimeter) (DC) 0 - 200 V at least 02 4 DC regulated power supply 0 - 30 V 02 5 Connecting wires, bread board or experimental kit
As required
Circuit diagram:
Theory: (I) Kirchhoff’s Voltage Law (KVL)
It is also called as Mesh analysis.
Analytical solution:
(II) Kirchhoff’s Current Law (KCL)
It is also called as Nodal analysis.
Analytical solution:
Calculation: (using measured values)
(I) Kirchhoff’s Voltage Law (KVL)
Sr. No.
Supply Voltages (V) Voltage drops, IR in (V)
V 1 V 2 I 1 x 460 I 2 x 330 I 3 x 220 (I 1 -I 2 ) x 720 (I 3 -I 2 ) x 680
1 10 15
∑ emf‟s + ∑ IR drops = 0
(II) Kirchhoff’s Current Law (KCL)
Sr. No.
Supply Voltages (V)
Current through Nodes (mA)
I 2 = (Va-Vb)
Result:
(I) KVL :
Sr. No. Theoretically Practically
1
At node Va I 1 - I 2 - I 3 = 0
At node Vb I 3 - I 4 +I 5 = 0 Sr. No. Theoretically Practically Theoretically Practically
1
Current flowing through 460 Ω => I 1 ………………… mA
Current flowing through 720 Ω => I 1 -I 2 ………………… mA
Current flowing through 330 Ω => I 2 ………………… mA
Current flowing through 220 Ω => I 3 ………………… mA
Current flowing through 680 Ω => I 3 -I 2 ………………… mA
Conclusion:
Theory:
Using the Thevenin‟s theorem any complicated circuit can be replaced by a single voltage source
in series with impedance this is called as Thevenin‟s equivalent circuit. The Thevenin‟s
equivalent circuit is simplified circuit of any complicated circuit. The theorem has provided a
powerful means of network analysis.
Statement:
Any two terminal network containing energy source and impedances can be replaced
with an equivalent circuit consisting of a voltage source VTH in series with impedance ZTH. The
value of VTH is the open-circuit voltage between the terminals of the network and ZTH is the
impedance measured between the terminals with all energy sources eliminated (but not their
impedances).
The Thevenin‟s equivalent will produce the same load current and voltage as the original circuit
to any load. Consequently, if many different loads or sub-circuits are under consideration, using
a Thevenin equivalent may prove to be a quicker analysis route.
Schematic of Thevenin’s equivalent :
Fig. 1. DC network
Fig.2. Thevenin‟s equivalent
Limitations of Thevenin Theorem :
Not applicable to the circuit of nonlinear elements
Not applicable to unilateral network.
There should not be magnetic coupling between the load & circuit to be replaced by
Thevenin‟s theorem.
circuit.
Analytical solution:
(I) Calculate Thevenin‟s voltage (VOC or VTH)
(II) Calculate Thevenin‟s resistance (ZTH)
(III) Calculate current flowing through load resistance RL i.e. IL
Result:
Sr. No.
Supply Voltages (V)
Thevenin’s voltage (V)
Thevenin’s Equiv. Resistance (Ω)
Load current (mA)
V 1 V 2 VOC or VTH ZTH IL
Theoretically 10 05
Practically
Conclusion:
Oral questions:
Aim: Verification of Superposition theorem
Objective: i. Apply Superposition theorem to find analytical values of the branch currents for the given DC network. ii. Measure the branch current of the network with both sources acting simultaneously and with each source acting alone. iii. Compare the analytical and measured values of currents.
Requirements:
Sr. No. Equipment / Instrument Device Rating/Value Quantity 1 Resistance 270 Ω 03
2 Resistance 100 Ω ,150 Ω, 27 Ω each 01 3 Current meter (DC) (Multimeter)
0 - 1 A at least 02
4 Volt meter (Multimeter) (DC) 0 - 200 V 01 5 DC regulated power supply 0 - 30 V 02 6 Connecting wires, bread board or experimental kit
As required
Circuit diagram:
Observations:
Sr. No.
Supply Voltages (V)
Current through 270 Ω (mA)
Current through 270 Ω (mA)
Current through 270 Ω (mA) V 1 V 2 I 1 I 1 ’ I 1 ’’
1 Both supply working
3 Only V 1 supply acting alone
Only V 2 supply acting alone
Calculation:
Result:
Current through branch (270 Ω resis)…
when V 1 = V acting alone, I 1 ‟ = -------------- mA.
when V 2 = V acting alone, I 1 ‟‟ = -------------- mA.
when V 1 & V 2 acting, I 1 = I 1 ‟+I 1 ‟‟ = ------------- mA. (Measured)
when V 1 & V 2 acting, I 1 = I 1 ‟+I 1 ‟‟ = ------------- mA. (Theoretically)
Conclusion:
Oral questions:
The power rating indicates how much power the resistor can safely tolerate. The
maximum rated power of the resistor is specified in Watts. Power is calculated using the
square of the current (I^2 ) x the resistance value (R) of the resistor. If the maximum rating of the
resistor is exceeded, it will become extremely hot and even bum.
b) Wire wound potentiometer
Resister Color Code:
Four & Five band resistor:
