B.Sc in Computer Science and Engineering
Experiment No: 02
Title of the Experiment: Determination of V-I characteristics of a
given resistance using Ohm’s Law.
LAB REPORT
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Experiment No: 02
Title of the Experiment: Determination of V-I characteristics of a
given resistance using Ohm’s Law.
Objective:
1. To represent Ohm’s Law graphically.
2. To draw V-I characteristics.
3. To draw circuit with the value of V, I and R.
Theory: Ohm's law states that the voltage or potential difference between two
points is directly proportional to the current or electricity passing through the
resistance, and directly proportional to the resistance of the circuit. The
formula for Ohm's law can be expressed as follows –
Formula of Voltage: For a constant
value of R, V is directly proportional
to I; i.e.
V=IR.
Where, V = voltage, I = current and
R = resistance. And their units are in
volt (v), ampere (A) and ohm (Ω)
respectively.
Formula of Current: For a constant
value of V, I is inversely proportional
to R; i.e.
I= .
Circuit Diagram:
Figure-1: Determination of V-I Characteristics
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Apparatus:
1. Resistor
4. Bread board
7. Trainer board
2. Ammeter
5. Resistor
8. Power supply
3. Voltmeter
6. Graph paper
9. Connecting wire etc.
Procedure:
1. Draw the required circuit.
2. Verify and check ammeter and voltmeter before starting.
3. Measure the value of V and note it down.
4. Take the reading of current (I) for different values of voltage (V)
5. Draw V-I curve.
6. Finally, verify and ensure that, heater value of resistance is the source as
taken from the curve.
Calculation:
Theoretical Value of Resistor (RT):- We can see that, there are four color
bands (Brown, Black, Red and Gold) printed on the resistor. Red is the
multiplier and Gold is the tolerance band. Each of the bands has significant
value. Using color code by putting the values of each band respectively, we
can determine the theoretical value of the resistor. The process is shown as
follows = Band1 Band2 x 10Band3 ± Band4
Theoretical Value, RT
= 10 x 102 ± 5 %
= 1000 ± 5 % Ω
Practical Value of Resistor (RP):- The practical value of the resistor is
measured by using the formula Practical Value, RP = .
Tolerance:- Tolerance of the resistor is measured by using the formula Tolerance, T =
x 100.
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Data Table:
Voltage
(V)
Current
(I)
[V]
[mA]
Theoretical
(RT)
[Ω]
Resistance (R)
Tolerance
Practical
(T =
x 100)
(RP = )
[Ω]
[%]
0
0
1
1.03
970.87
2.60
3
3.08
974.03
2.91
5
5.15
970.87
2.51
7
7.18
974.93
2.91
9
9.27
970.87
3.01
10
10.31
969.93
2.36
12
12.29
976.40
2.71
14
14.39
972.90
1.45
15
15.22
1000 ± 5 %
985.55
Table-1: Ohm’s Law Verification Table
Data Plotting:
Graph-1: Ohm’s Law Verification Graph
1.45
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Analysis: From the table-1 we see that, the measured tolerances at different
readings are within the limit (± 5 %). Moreover, from the graph-1 we see that,
the measured real or practical values represented by blue dots are almost on
the green line. And the green line is nothing but represents the theoretical
value. Therefore, it is considered that, the experiment is satisfactory.
Safety:
1. General safety precautions of lab are carried out strictly.
2. STP is maintained in the lab.
3. The multimeter is calibrated one.
4. Bread board’s row and column wise internal feature is considered for series
and parallel connection.
5. Consciousness is maintained about human and instrumental error.