Electrical Resistance in Series and Parallel Circuit

PHY098
LABORATORY PRESENTATION ON LAB REPORT
ELECTRICAL RESISTANCE IN SERIES AND PARALLEL
CENTER OF FOUNDATION STUDIES, UITM DENGKIL
PI009E26
DATE PERFORMED : 19TH JANUARY 2019
LAB INSTRUCTOR : PROFESSOR MADYA DR. MOHD AZAM BIN ABDUL RAHMAN

GROUP
MEMBERS
 AZRUL HAKIMI BIN AZMI
2018427662
 IRFAN RASYIDI BIN KAMARUDIN
2018218346
 IZZAM HARITH BIN MOHD. KAMARUL ARIFIN
2018209862
 MUHAMMAD NAZREEN SHAH BIN HABEEB
RAHMAN
2018681214
 MUHAMMAD ISKANDAR ZULQARNAIN BIN MOHD
ISHAK
2018294362

ABSTRACT
PURPOSE
• This
experimen
t should
show you
the
difference
between
resistors in
series and
OBJECTIVE
• To
determine
the
equivalent
resistance
for
resistors
connected
in METHOD
• In this
experiment, two
circuits will be
set up, one with
resistors in
series, one with
resistors in
parallel. The
total resistance
of both electric
circuit is
calculated. The

THEORY
For parallel circuit :
• Parallel resistors experience the same voltage,
• but different currents.
For series circuit :
• Series resistors experience the same current, but different voltages.
The resistance, R of an object can be defined as the ratio
of voltage, V across it to the current, I flows through it.

INTRODUCTION
A resistor is an Ohmic indicating
instrument that provides
specialty electrical resistance to
the flow of charges in particular
electric circuit.
Resistors are used to control currents
and voltages, which very highly
utilised in electrical appliances.
There are several types of
resistors invented in this
worldwide usage. Meanwhile,
the Carbon (C) coated resistors
such a common type used in
industry.
Carbon resistors come in much range,
which indicated using colour-coded
circular bands.

METHODOLOGY
1.The apparatus was
assembled according to
Figure 1 below.
1.The voltage of the
power supply was set to
2V DC.
1.Both voltage on the
voltmeter and current
on the ammeter were
recorded in a table.
Step 2 and Step 3 were
repeated by increasing
the voltage reading of
the power supply.
A. Connection for resistors in Series circuit

METHODOLOGY
A. Connection for resistors in Parallel circuit
1.The apparatus was
assembled according to
Figure 2 below.
1.The voltage of the
power supply was set to
2V DC.
1.Both voltage on the
voltmeter and current
on the ammeter were
recorded in a table.
Step 2 and Step 3 were
repeated by increasing
the voltage reading of
the power supply.

RESULTS & ANALYSIS
Voltage of
power
supply (V)
Voltage,
V (V)
Current, I (A) Resistance, Ω
1st reading 2nd reading 3rd reading Average
reading
2 1.998 0.001 0.002 0.001 0.0013 1537
4 3.995 0.003 0.002 0.003 0.0027 1479
6 6.000 0.004 0.004 0.004 0.004 1500
8 8.000 0.005 0.006 0.005 0.0053 1509
10 10.01 0.007 0.007 0.007 0.007 1430
Average resistance 1242.5
RESULT IN SERIES CIRCUIT

RESULT IN PARALLEL CIRCUIT
Voltage of
power
supply (V)
Voltage,
V (V)
Current, I (A) Resistance, Ω
1st reading 2nd reading 3rd reading Average
reading
2 1.994 0.029 0.029 0.029 0.029 68.76
4 4.000 0.060 0.060 0.060 0.060 66.67
6 6.000 0.090 0.090 0.090 0.090 66.67
8 8.000 0.121 0.121 0.121 0.121 66.12
10 10.00 0.153 0.153 0.153 0.153 65.36
Average Resistance 66.72
RESULTS & ANALYSIS

RESULTS & ANALYSIS
1) Resistance (experimental data)
𝑉 = 𝐼𝑅
𝑅 =
𝑉
𝐼
In series:
𝑅 = 1242.5 Ω
In parallel:
𝑅 = 66.72 Ω
1)

In this experiment, we obtained three different resistance values using experimental
method, theoretical method and graphical method.
1) Resistance calculated using colour code (theoretical method):
In series:
𝑅 = 𝑅1+ 𝑅2 + 𝑅3
𝑅 = 130 + 250 + 660
𝑅 = 1040 Ω
In parallel:
1
𝑅
=
1
𝑅1
+
1
𝑅2
+
1
𝑅3
1
𝑅
=
1
130
+
1
250
+
1
660
𝑅 = 75.71 Ω
RESULTS & ANALYSIS
2

RESULTS & ANALYSIS
1) The slope of the graph (1 𝑅)
In series:
𝑠𝑙𝑜𝑝𝑒 =
0.0061 − 0.0011
8.8 − 2.1
= 7.4627 × 10−4
𝑅 =
1
𝑠𝑙𝑜𝑝𝑒
=
1
7.4627 × 10−4
= 1340 Ω
𝑃𝑒𝑟𝑐𝑒𝑛𝑡𝑎𝑔𝑒 𝑒𝑟𝑟𝑜𝑟 =
𝑡ℎ𝑒𝑜𝑟𝑒𝑡𝑖𝑐𝑎𝑙 𝑣𝑎𝑙𝑢𝑒 − 𝑒𝑥𝑝𝑒𝑟𝑖𝑚𝑒𝑛𝑡𝑎𝑙 𝑣𝑎𝑙𝑢𝑒
𝑡ℎ𝑒𝑜𝑟𝑒𝑡𝑖𝑐𝑎𝑙 𝑣𝑎𝑙𝑢𝑒
× 100%
=
1040 − 1340
1040
× 100%
= 28.85%
3)

RESULTS & ANALYSIS
In parallel:
𝑠𝑙𝑜𝑝𝑒 =
0.144 − 0.016
9.5 − 1.1
= 0.015238
𝑅 =
1
𝑠𝑙𝑜𝑝𝑒
=
1
0.015238
= 65.62 Ω
× 100%
=
75.71 − 65.62
75.71
× 100%
= 13.33%

RESULTS & ANALYSIS
1) Percentage error (calculated from data)
× 100%
In series:
=
1040 − 1242.5
1040
× 100%
= 19.47%
In parallel:
=
75.71 − 66.72
75.71
× 100% = 11.87%
4)

660Ω, 250Ω and 1300Ω
resistors connected to a
series circuit and a parallel
circuit using connecting
wires.
Voltage of 2V,4V,6V, 8V
and 10V from power supply
were used to gave readings
to ammeter applied on
both of the circuits.
Readings were recorded in
table 1 for series and table
2 for parallel.
In series circuit, I=I1=I2=I3
while in parallel circuit,
I=I1+I2+I3
In series circuit, V=V1+V2+V3
while in parallel circuit,
V=V1=V2=V3
DISCUSSIONS

From calculation, resistance value for series
is 1242.5Ω while for parallel is 66.72Ω.
From graph, resistance value for series is
1340Ω while for parallel is 65.62Ω.
Both of the values was different to theoretical
but still in acceptable range.
Both of the circuit’s graph of current versus
voltage resulted expected straight line.
The slope of the line for series circuit was
0.442 mA/V (1/R), while parallel circuit was
3.690 mA/V.
Experiment was success by using Ohm’s Law. It
obeys Ohm’s Law which states that current is
directly proportional to voltage.

SOURCE OF ERRORS
• Longer length of wire,
higher resistance in wire.
• Due to the large scale of
reading.
• Quite thick, causes high
internal resistance.
• Accuracy of components
decreases and supply might
display wrong results.
Variable DC
power supply.
Radius of the
connecting
wire.
Length of the
connecting
wire.
Inaccurate
reading of
multimeter .
DISCUSSIONS

Electrical Resistance in Series and Parallel Circuit

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