Determining wave frequency from a graph

Determining wave frequency
from a graph

f
• Frequency = #of cycles/time
• Measured in Hertz (Hz)

• 1 cycle = 1 full wave to
repeat itself

31 2 4 5 6 7 8 9 10 11 12
Time in seconds
3 cycles

from 0 to 12 seconds
31 2 4 5 6 7 8 9 10 11 12
Time in seconds
0

f=3 /12 s = ¼ Hz
31 2 4 5 6 7 8 9 10 11 12
Time in seconds

• Or determine the time for 1 full wave cycle

1 cycle in 4 seconds= ¼ Hz
31 2 5 6 7 8 9 10 11 12
Time in seconds
0 4

• Period symbol T
• The time for 1 cycle

The period for 1 wave is 4
seconds T=4
31 2 4 5 6 7 8 9 10 11 12
Time in seconds

What is the frequency?
0 2 4 6 8 10 12 14 16 18 20
Time in seconds
22 24

?
0 2 4 6 8 10 12 14 16 18 20
Time in seconds
22 24
3 cycles 0 to 24 seconds

0 2 4 6 8 10 12 14 16 18 20
Time in seconds
22 24
3 cycles 0 to 24 seconds3/24 s= 1/8 Hz

OR
• Frequency – 1 cycle in x seconds

f=1 cycle in 8 seconds= 1/8 Hz
0 2 4 6 8 10 12 14 16 18 20
Time in seconds
22 24

• On a piece of paper
number 1 through 3 and
determine the frequency
of the following waves.

#1 f= ?
0 1 2 3 4 5 6 7 8 9 10 11 12
Time seconds

#2 f= ?
Time seconds
0 2 4 6 8 10 12 14 16 18 20 22 22 24 26

#3 f = ?
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70
Time seconds

#1 f= 1/8 Hz
0 1 2 3 4 5 6 7 9 10 11 12
Time seconds
8

#2 f= 1/8 Hz
Time seconds
0 2 4 6 10 12 14 16 18 20 22 22 24 268

#3 f = 1/20 Hz
0 5 10 15 25 30 35 40 45 50 55 60 65 70
Time seconds
20

Determining wave frequency from a graph

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