8.2 Pitch and frequency

8.2 Pitch and frequency
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Natuurkunde / ScheikundeMiddelbare schoolhavo, vwoLeerjaar 2

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8.2 Pitch and frequency

Slide 1 - Diapositive

Schedule for this lesson
Explanation the period and frequency of a vibration

Apply knowledge by doing exercises in the workbook







Slide 2 - Diapositive

Learning objectives 1/2
-You can write down three factors that affect how high the tone is that a string produces

- You can explain what the frequency of a vibration is

- You can determine the vibration period of a tone in an oscilloscope trace

- You can do calculations using the vibration period and frequency



Slide 3 - Diapositive

Learning objectives 2/2
-You can give the frequency range of human hearing


Slide 4 - Diapositive

The vibration period and frequency
When a sound is made a vibration is given off

We can see these vibrations in so called oscilloscopes 

Slide 5 - Diapositive

The vibration period and frequency
Each square on the oscilloscope gives an amount of time
(1 square is 0,5ms)

And each vibration takes a certain
amount of time to complete




Slide 6 - Diapositive

The vibration period and frequency
The vibration period is the amount of time it takes to complete 1 full vibration

In this picture we see multiple vibrations, at which point(s) do we see a completed vibration?

Slide 7 - Diapositive

The vibration period and frequency
With the time 1 square takes up, and the amount of completed vibrations we can calculte the vibration period (T)

For example, we have 
3 completed vibrations

What is the time for these 3 vibrations?

Slide 8 - Diapositive

The vibration period and frequency
We divide the time it takes to complete a certain amount of vibrations with the amount of vibrations and we get the vibration period (T)

T = 2,4/3=0,8ms = 0,0008

Slide 9 - Diapositive

The vibration period and frequency
If we know the period of a vibration we can calculate its frequency (f) in Hertz (Hz)

We can do this with the formula 
f = 1/T




Slide 10 - Diapositive

The vibration period and frequency
The frequency means the amount of vibrations that happen over 1 second

For example, if the vibration period is 0,1 s, there are 10 vibrations in 1 s
1/0,1=10

Slide 11 - Diapositive

The vibration period and frequency
When we calculated T we got the answer of 0,8ms
Now we can calculate the frequency

f=1/0,0008=1250Hz
Which means 1250 vibrations per second

Slide 12 - Diapositive

The vibration period and frequency
Calculate f with a vibration period of...

0,004ms

39ms

and with 0,011

Slide 13 - Diapositive

The vibration period and frequency
We humans are able to hear sounds with low and high frequencies

Our hearing range is between 20hz and 20000hz

We can visualize these sounds with a video

Slide 14 - Diapositive

Slide 15 - Vidéo

Playing a game with the exercises
I have an excel sheet in which i can give points to a team

The amount of point you can get is different each exercise (and is shown on the sheet)

For the rest of the lesson you will make these exercises on a piece of paper, when you are done with 1 exercise you come to me and I will check it

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Playing a game with the exercises
When you are correct you will go to the next exercise and you get all points

When you are incorrect you will lose a point, but if you correct the mistake you can still earn a few points. If you are correct after correcting the mistake you will go to the next exercise 

Slide 17 - Diapositive

End of the lesson

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