Experiment Number: E1
Experiment Name: Verification of ohm’s law and laws of series and
parallel resistance.
Course Name: Physics 102
Course ID: 102 L
Section: 14
Submitted to
Faculty Name: Md. Saddam Sheikh
Department of Physical Sciences.
School of Engineering and Technology
Independent University, Bangladesh.
Submitted by
Muhammad Waez Mahmud
2312148
Department of Computer Science and Engineering.
Email: 2312148@iub.edu.bd
Experiment Name: Verification of ohm’s law and laws of series and
parallel resistance.
Theory: Ohm's law states that the current through a conductor between two points is
directly proportional to the voltage across the two points. Introducing the constant of
proportionality, the resistance, one arrives at the usual mathematical equation that describes
this relationship:
𝑉
𝐼 = , where V is the potential difference across the resistance R.
𝑅
When several resistors are connected in series their equivalent resistance Rs is given by
Rs = 𝑅1 + 𝑅2 + … …. …
Again, when the resistors are connected in parallel the equivalent resistance of their
combination Rp is given by
1
1
=
𝑅𝑝
1
+ … …. ….
+
𝑅1
𝑅2
Equipment:
i)
ii)
iv)
v)
Power supply,
variable resistance, iii) ammeter,
voltmeter,
unknown resistance, vi) key.
Experimental Data Table:
Table 1: Voltage current records for 𝑹𝟏 𝒂𝒏𝒅 𝑹𝟐
I (amp)
V(volt)
0
0.06
0.12
0.19
0.24
0
0.03
0.06
0.09
0.13
R1
(47Ω)
R2
(100Ω)
0
3.12
6.02
9.00
11.97
0
3.15
6.11
9.05
12.15
Table 2: Voltage current records for series and parallel connection
Resistance
R1 And R2 in Series
R1 And R2 in Parallel
I(amp)
0
0.02
0.04
V(volt)
0
3.24
6.27
0.06
9.25
0.08
0
12.22
0
0.09
3.04
0.18
0.27
0.36
5.90
8.90
11.79
Table 3: Verification of laws of series and parallel resistance:
Resistors
𝑹𝟏 Ω
𝑹𝟐 Ω
Experimental
Value Ω
(From
Graph)
Comment
(153.84−147)
Series
Combination
147Ω
47Ω
Parallel
Combination
Calculated
Value
(Ω)
153.84Ω
147
× 100% = 4.65%
100Ω
31.97Ω
32.31Ω
(32.31−31.97)
31.97
×100% = 1.06 %
Graphs:
0.09
0.08
y = 0.0065x
Current I(amp)
0.07
0.06
0.05
0.04
0.03
0.02
0.01
0
0
2
4
6
8
10
12
14
Voltage V(volt)
Graph 1: (I vs V for R1), Equation: y = 0.0065x
0.14
y = 0.0103x
0.12
Current I(amp)
0.1
0.08
0.06
0.04
0.02
0
0
2
4
6
8
10
12
Voltage V(volt)
Graph 2: (I vs V for R2), Equation: y = 0.0103x
14
0.09
0.08
y = 0.0065x
0.07
Current I(amp)
0.06
0.05
0.04
0.03
0.02
0.01
0
-0.01
0
2
4
6
8
10
12
14
Voltage V(volt)
Graph 3: (R1 and R2 in series), Equation: y = 0.0065x
0.4
y = 0.0309x
0.35
Current I(amp)
0.3
0.25
0.2
0.15
0.1
0.05
0
0
2
4
6
8
10
12
Voltage V(volt)
Graph 4: (R1 and R2 in Parallel), Equation: y = 0.0309x
14
Calculation and Result:
Given that ,
R1= 47𝛀
R2=100 𝛀
So,
Rs = (R1 + R2) = (47 + 100) Ω = 147Ω And
1
Rp = (
𝑅1
1
1
𝑅2
47
+ )−1 = (
+
1
100
)
−1
147 −1
)
4700
=(
= 31.97 𝛀
From I vs V for R1 and R2 in series graph the slope of the trendline is 0.0065,
Y = mx +C =0.0065x + C ∴ slope, m = 0.0065
1
1
So, Rs = 𝑉𝐼 = 𝑠𝑙𝑜𝑝𝑒(𝑚)
=
= 153.84𝛀
0.0065
From I vs V for R1 and R2 in parallel graph the slope of the trendline is 0.0309
Y= mx + C = 0.0309x + C ∴ slope, m = 0.0309
1
1
So, Rp = 𝑉𝐼 = 𝑠𝑙𝑜𝑝𝑒(𝑚)
=
=32.31𝛀
0.0309
Result: we get R1 = 47 Ω, R2 = 100 Ω.
Respectively, from the graph Rs = 153.84 Ω , Rp = 32.31 Ω .
Discussion:
i)
Data analysis: we take 2 resistors for this experiment. For current calculation, we
connect ammeter in series of that circuit. Then we get 5 different values for each
R1 and R2. We calculate Voltage, we connect voltmeter in parallel in the circuit.
after that we connect resistor in series and parallel to get Rs and Rp value. We
initially change the data because there was huge amount of error in the
experiment.as we did not get the straight line with the provided data in the sheet in
table 1 and table 2 both.
For table 1, R1 values are (0,0) , (3.12V , 0.06A),( 6.02V , 0.12A), ( 9.0V , 0.19A),
(11.97V , 0.24A).
For table 1, R2 values are (0,0) ,(3.15V , 0.03A), (6.11V , 0.06A), (9.05V , 0.09A),
(12.15V , 0.13A).
For table 2, Rs values are (0,0), (3.24V , 0.02A), (6.27V ,0.04A), (9.25V , 0.06A),
(12.22V , 0.08A).
For table 2, Rp values are (0,0), (3.04V , 0.09A), (5.90V , 0.18A), (8.90V , 0.27A),
(11.79V , 0.36A).
ii)
Graph analysis:
In I vs V from Rs graph the slope of the trendline is 0.0065 and the equation of the
trendline Y = mx + C = 0.0065x +C. The actual equation is Y= mx + c, so slope is
0.0065 and Rs = 153.84 Ω (Graphical value).
In I vs V from Rp graph the slope of the trendline is 0.0309 and the equation of the
trendline Y = mx + C = 0.0309x + C. The actual equation is Y= mx + c, so slope is
0.0309 and Rs = 32.31 Ω (Graphical value).
We found some error using the following values,
Error =
iii)
(𝑒𝑥𝑝𝑒𝑟𝑖𝑚𝑒𝑛𝑡𝑎𝑙 𝑣𝑎𝑙𝑢𝑒−𝑒𝑥𝑝𝑒𝑐𝑡𝑒𝑑 𝑣𝑎𝑙𝑢𝑒)
𝑒𝑥𝑝𝑒𝑐𝑡𝑒𝑑 𝑣𝑎𝑙𝑢𝑒
Result analysis: we get R1 = 47 Ω, R2 = 100 Ω, Rs = 147 Ω and Rp = 31.92 Ω. after
analysis of all data, we concluded that for every voltage increase, the current flow
increases which follow ohm’s law which is I ∝ V. We find error for series and
parallel connection,
For series: Error =
(153.84−147)
For parallel: Error =
iv)
× 100%
147
× 100% = 4.65%
(32.31− 31.97)
31.97
× 100% = 1.06%
Precaution: To connect the Voltmeter and Ammeter in the circuit very carefully.
We must Connect the ammeter in series and voltmeter in parallel in the circuit. after
measuring the data carefully listed down in the report sheets.