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Define voltage and give its unit of measurement.
Identify the two different types of voltmeters.
Connect a voltmeter in a circuit to measure voltage.
Use a digital multimeter to measure voltage.
Define current and give its unit of measurement.
Connect an ammeter in a circuit to measure current.
Use a digital multimeter to measure current.
Define resistance and give its unit of measurement.
Determine the resistance value using the resistor color
code chart.
Use a digital multimeter to measure resistance.
1.1 Introduction
1.2 Voltage Measurement
1.3 Current Measurement
1.4 Resistance Measurement
1.5 Lab Activity 1
1.6 Lab Activity 2
1.7 Module Exercise
Page No.
wall outlet/power socket
DC: Direct Current
In DC, the flow of electric charge is only in one direction. DC is
Produced by a battery and is used to power portable devices
such as the
 cell phones,
 iPods, etc.
AC: Alternating Current
In AC, the flow of electric charge periodically reverses direction. AC
Is generated in a powerplant and is delivered to the electric outlets
in your home and buildings.
 Washing machines,
 television,
 water
 heater etc. operate on ac.
Note: See Video
Sources- Solar Panel
Source – Power Plant
Voltage is the electric force that drives
current around an electric circuit.
Unit of voltage is volt,
 Symbol is ‘V’.
A voltmeter is used to measure voltage.
There are two types of voltmeters
Analog Voltmeter
Digital Voltmeter
The analog multimeter
measures voltage by
deflecting a needle against
a scale.
A digital multimeter displays
the voltage value in digits.
Note: Voltage and other electrical quantity may
also be measured using a digital multimeter
Set the multimeter knob to
read voltage (dc or ac) and
select the range.
 Connect the two probes
with proper polarity in
parallel with the
component/device, across
which the voltage is to be
Switch ON the meter and
read the voltage.
Note: For unknown voltages, it is better to begin with the biggest
range, and then reduce the range as this will protect the meter
Connect a voltmeter to
measure the total voltage
supplied by the battery.
Connect voltmeters to
measure the voltages across
each of the three bulbs.
Current is a measure of the flow of electrons in an
electric circuit.
 Current is measured in amperes (A) and is denoted by
the symbol ‘I’
Current can also be measured with a
Set the multimeter knob to read current (dc
or ac) and select the range.
Break the circuit and insert the multimeter
probes across the break to
complete the circuit.
Switch ON the meter and read the current
Resistance is a measure of the opposition
to the flow of current. It is measured in
ohms (Ω) and is denoted by the symbol
Is resistance good or bad?
Resistance can be both good and bad. If we are
trying to transmit electricity from one place to
another through a conductor, resistance is
undesirable in the conductor.
 The heat that is generated from electric heaters or
the light that we get from light bulbs is due to
Color1 Color2 x 10Color3
Calculate the resistance of the
resistor which has the following
color code:
Red Green Red Gold
R = Color1 Color2 x 10Color3
= 2 5 X 102
= 2500Ω = 2.5kΩ.
Tolerance= + 5%.
Therefore, R =2.5kΩ+ 5%
V=I x R
› R = Resistance
› V = Voltage
› I = Current
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