Determining wave frequency from a graph f Frequency

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Determining wave frequency from a graph

Determining wave frequency from a graph

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

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

 • 1 cycle = 1 full wave to repeat itself

• 1 cycle = 1 full wave to repeat itself

3 cycles 1 2 3 4 5 6 Time in seconds 7 8 9

3 cycles 1 2 3 4 5 6 Time in seconds 7 8 9 10 11 12

from 0 to 12 seconds 0 1 2 3 4 5 6 Time in

from 0 to 12 seconds 0 1 2 3 4 5 6 Time in seconds 7 8 9 10 11 12

f=3 /12 s = ¼ Hz 1 2 3 4 5 6 Time in

f=3 /12 s = ¼ Hz 1 2 3 4 5 6 Time in seconds 7 8 9 10 11 12

 • Or determine the time for 1 full wave cycle

• Or determine the time for 1 full wave cycle

1 cycle in 4 seconds= ¼ Hz 0 1 2 3 4 5 6

1 cycle in 4 seconds= ¼ Hz 0 1 2 3 4 5 6 Time in seconds 7 8 9 10 11 12

 • Period symbol T • The time for 1 cycle

• Period symbol T • The time for 1 cycle

The period for 1 wave is 4 seconds T=4 1 2 3 4 5

The period for 1 wave is 4 seconds T=4 1 2 3 4 5 6 Time in seconds 7 8 9 10 11 12

What is the frequency? 0 2 4 6 8 10 12 14 Time in

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

? 3 cycles 0 2 4 6 8 10 12 0 to 24 seconds

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

0 to 24 seconds 3/24 s= 1/8 Hz 3 cycles 0 2 4 6

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

OR • Frequency – 1 cycle in x seconds

OR • Frequency – 1 cycle in x seconds

f=1 cycle in 8 seconds= 1/8 Hz 0 2 4 6 8 10 12

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

 • On a piece of paper number 1 through 3 and determine the

• 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 Time seconds 8

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

#2 0 2 4 6 8 10 12 f= ? 14 16 Time seconds

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

#3 f = ? 0 5 10 15 20 25 30 35 40 Time

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

 • Check your answers

• Check your answers

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

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

#2 0 2 4 6 8 10 f= 1/8 Hz 12 14 16 Time

#2 0 2 4 6 8 10 f= 1/8 Hz 12 14 16 Time seconds 18 20 22 22 24 26

#3 f = 1/20 Hz 0 5 10 15 20 25 30 35 40

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