Engineering Measurement Lab Report

This lab report provides an introduction to the Ohm's law and its application in household electrical circuits. It explains the use of series and parallel connections in lighting small and large rooms and the measurement of resistors using color codes or a multimeter. The report includes two tasks: familiarization of instruments and components and series and parallel circuits. The results and observations show that current remains the same in the series circuit connection but it varies in the parallel circuit connections. The variance is measured using the Kirchhoff’s current law.

2018
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ENGINEERING MEASUREMENT LAB REPORT
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ENGINEERING MEASUREMENTS LAB REPORT
INTRODUCTION
Basic overview
There are common household electrical circuits which mainly operate on the Ohm's law. Many
of these components are connected in parallel. The electric circuits in these devices are
connected to the power source and draw from the source in different amounts depending on the
value of the resistors in the circuit design. The electric components have a power supply and
loads which get the supply. Hence, there is a direct proportionality between the potential
difference of a circuit and the resistance component.
The Ohm's law is given as
V =IR
The use of series and parallel connections is applied to light the small rooms and very huge
rooms. The Kirchhoff’s current and voltage laws are used in the parallel connections while the
summation expressions are used in the series connections. The resistors are measured using color
codes or measured using a multimeter,
EXPERIMENT
TASK 1: FAMILIARIZATION OF INSTRUMENTS AND COMPONENTS
Aim:
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(i) To determine the functions and purpose of the series and parallel components in the
circuit design.
Components and Instruments
(i) DC generator (Power supply)
(ii) Micrometer
(iii) Resistors (series/parallel unit)
(iv) Ammeter and voltmeter
Discussion
The DC generator is included in the circuit as the point of power supply. It provides 20 volts to
the channel. The micrometer is used in the measurement of lengths. The resistors are used to give
the resistance component in the loop. The ammeter measures the current flowing through the
loop while the voltmeter measures the potential difference across each element on the channel.
TASK 2: SERIES AND PARALLEL CIRCUITS
Aim
(i) To determine the behavior of circuits and current flow in series and parallel
connections.
Circuit designs (series and parallel circuits)
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Procedure
(i) The power supply is connected at 20 volts in AC mode.
(ii) Four resistors are connected as demonstrated in the series and parallel connections as
shown in the circuit diagram figure 2.
(iii) The readings of voltage and current for each resistor in series and parallel connections
were recorded in tables.
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(iv) The results and observations were discussed and conclusions made.
Results and observation
Part1: Series circuit
Resistors in Series
Parameters Resistance (ohms) Voltage (v)
Resistor #1 330 3.564
Resistor #2 120 1.296
Resistor #3 401 4.330
Resistor #4 1000 10.81
Total Resistance 1851 ohms
Total current 10.799 mA
Resistor 2 (color codes)
R2=brown , red , black , gold=120 ± 5 %
R3= yellow , black , brown , gold=401 ± 5 %
330 120 401 1000
0
2
4
6
8
10
12
Plot of potential difference against
resistance
current
Resistor (ohms)
potential Difference (volts)
Part2: Parallel circuits
Resistor R3 and R4 are in parallel hence
R2∨¿ R3= R2 R3
R2+ R3
= 120∗401
120+ 401=92.361 ohms
The equivalent circuit resistance is given as
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Reqv=R1+ ¿
Reqv=330+ 92.361+1000
Reqv=1422.361ohms
i1=i2+ i3
Resistors in Series
Parameters Resistance (ohms) Current (Amps)
Resistor #1 330 0.061
Resistor #2 120 0.018
Resistor #3 401 0.043
Resistor #4 1000 0.061
Total Voltage 20V
Equivalent Resistance 1422.361 ohms
330 120 401 1000
0
0.01
0.02
0.03
0.04
0.05
0.06
0.07
Current Behaviour in Parallel circuits
Conductance
Resistor (ohms)
current (amps)
Discussion
For a series connection, the current across each resistor is the same as the current at the power
source, such that,
I input=Ir 1=I r 2 =I r 3 =Ir 4
The voltage, on the other hand, is dependent on the resistance of each resistor on the circuit. The
sum total of potential differences across all the component equals the voltage at the source, such
that,
V source=V r 1+V r 2+V r 3 +V r 4
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The equivalent value of the resistors in the circuit are given as,
REquivalent=R1 +R2 + R3 +R4
For a parallel connection, the resistors have different amounts of current flowing through them
based on the Kirchhoff’s current law. The potential difference for all the resistors is equal.
CONCLUSION
In a nutshell, the series and parallel connections demonstrate different current and voltage
readings. The results and observations show that current remains the same in the series circuit
connection but it varies in the parallel circuit connections. The variance is measured using the
Kirchhoff’s current law.
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