A
Sine wave has a frequency of 6 Hz. What is its period?
Problems
4.3
Solution
f = 1=1=0.17 sec
f 6
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Problems 4.5
A
Sine wave completes one cycle in 4 seconds. What is its frequency?
Solution:
f=1 =1=0.25Hz
t 4
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Another Way to
look at Frequency
o Measurement of the rate of change
o The rate at which a sine wave moves from
its lowest to its highest point is its
frequency
o A 40 Hz signal has half the frequency of
a 80 Hz signal, therefore each cycle
takes twice
as long to
complete one cycle
I.e. to go
from its lowest
to its
highest
o Change in a short Time = High Frequency
Two
Extremes Frequency
o What if a signal does not change at all?
o What if it maintains a constant voltage
level the entire time?
9 In such cases , Frequency is going to be
zero
o If a signal does not change, it will
never complete any cycles, and frequency is
no.
of cycles in 1 second so Freq = 0
o No change at all ⇒
- Zero frequency
o Instantaneous changes ⇒
- Infinite frequency
Phase
o Phase describes the position of the
waveform relative to time zero
o If
we think of
the wave as
something that can
be shifted backward
or forward
along
the time axis
o Phase describes the amount of that shift
o It indicates the status of the first
cycle
o Phase is measured in Degrees or Radians
o 360 degrees - 2 pi Radians
o A phase shift of 360 degrees correspond
to a shift of a complete period
o A phase shift of 180 degree correspond to
a shift of half a period
o A phase shift of 90 degree correspond to
a shift of quarter a period
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