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Information Systems
Section 2
Quick Quiz
4.2.a
Name the types of electromagnetic waves used in communication
4.2.b
Name two advantages of microwaves over radio waves in communication.
4.2.b
Name two advantages of radio waves over microwaves in communication.
4.2.c
Complete the table below. An example has been completed for you
Part of the
Communication technology
electromagnetic spectrum
using part of the EM spectrum
Microwaves
Mobile phones
Satellite TV systems
Infra red
FM radio waves
4.2.i
Draw an amplitude modulated waveform.
4.2.i
What is meant by modulation?
4.2.i
Name two important pieces of equipment needed to observe wave modulation.
4.2.i
What is a first hand investigation?
HSC Style Questions
1. A student had to perform an investigation to observe ways in which waves can be modulated to
carry different types of information.
Describe how such an investigation could be carried out.
HSC Style Questions
1. A student had to perform an investigation to observe ways in which waves can be modulated to
carry different types of information.
Describe how such an investigation could be carried out.
9.4.2.ii
H3, H11
Marking Criteria
2-6
[4 marks]
Marks
4
Marks
Possible Answer
 Modulation means to change the amplitude or frequency of a
wave by using a lower order frequency.
 There are two kinds of modulation:
 Amplitude Modulation (AM). The amplitude of the radio wave
is increased or decreased according to the amplitude of the
audio signal.
 Frequency Modulation (FM). The frequency of the radio
wave is increased or decreased according to the frequency of
the audio signal. This is done at a higher frequency than
amplitude modulation.
 A Cathode Ray Oscilloscope can be used to view waves. The
waves are converted into electrical vibrations using various
devices such as a microphone.
 Use an oscilloscope to observe and draw signals that produce
various electrical currents.
o Audio signals produced by a tuning fork (using microphone)
o Voice signals produced by a speaking into a microphone
o An amplitude modulated signal produced by AM radio
o Attempt to view a frequency modulated signal produced by
FM radio stations (this may be beyond the limit of the CRO)
 Use text books to clarify what can be seen on the Cathode Ray
Oscilloscope