5.4: Loudness, Amplitude and oscilloscopes

• Science
• Middelbare school
• vwo
• Leerjaar 2

Learning  objectives 

• Name the four properties of a wave (wavelength, amplitude, frequency, speed).

• Describe how the amplitude of a sound wave influences the sound it produces.

• Be able to read waveforms correctly.

• Name the formula for calculating frequency (f = 1/T) and be able to apply it in calculations

• Name the formula for wave speed (v = f x λ) and be able to apply it in calculations.

  

Four wave properties

1. Wave length

2. Amplitude

3. Frequency 

4. Speed

Other examples of waves

v=f⋅λ

Assignment:

The time that it takes for one complete wave cycle is 0,0025 s. Calculate the frequency and the speed of the wave.

G:  T= 0,0025 s

A:  f=? v=?

 F:  f=1/T

  C: f= 1/0,0025 = 400 Hz

DO

Read textbook page 100 and 101

Do questions textbook page 101

Do questions workbook page 48

Questions and answers 

https:

It takes one soundwave to complete one wave in 0,0025s.
Calculate the frequency

Open: https://www.szynalski.com/tone-generator/
In the recording a frequency of 500 Hz is used. Using the tone generator: play this tone. If you increase the frequency:
A. What do you hear?
B. What is the maximum frequency you can hear?

If you decrease the frequency:
A. What do you hear?
B. What is the maximum frequency you can hear?

Change the seconds/div to 2 ms
A. How much time does it take for 1 wave to complete
B. According to your measurement: what is the frequency?
C. Is this answer different to the previous question?

Using the information of the previous 2 pages:
A. How much time does it take for 1 wave to complete
B. According to your measurement: what is the frequency?

Put input to: live input (5V peak amplitude)

Make some noise. Loud and less loud. What happens to the amplitude?

Using an oscilloscope: how can you see the loudness of a sound

What can you read from a waveform shown on an oscilloscope

1a.)  How many waves do you count in each of the following three pictures? 

Image 1

1a.)  How many waves do you count in each of the following three pictures? 

Image 1:

One wave.

Image 1

1b.) How many waves do you count in each of the following three pictures? 

Image 2

1b.) How many waves do you count in each of the following three pictures? 

Image 2

Image 2:

Two waves

1c.) How many waves do you count in each of the following three pictures? 

Image 3

1c.) How many waves do you count in each of the following three pictures? 

Image 3

Image 2:

Four waves

2a.)  If one block is 2cm wide, what is the wave length of this wave?

Image 1

2a.)  If one block is 2cm wide, what is the wave length of this wave?

Image 1

Image 2:

16 cm

2b.)  If one block is 2cm wide, what is the wave length of this wave?

Image 2

2b.)  If one block is 2cm wide, what is the wave length of this wave?

Image 2

Image 2:

8 cm

2c.)  If one block is 2cm wide, what is the wave length of this wave?

Image 3

2c.)  If one block is 2cm wide, what is the wave length of this wave?

Image 3

Image 2:

4 cm

3) Which of these two waves has a higher amplitude? Explain.

Image 1

Image 2

3) Which of these two waves has a higher amplitude? Explain.

Image 1

Image 2

4) Listen to these two sounds. Of which does the sound wave have a higher amplitude?

Sound A

Sound B

• Make sure to be in presentation mode.
• Click the icon to play the sound.
  
• Make sure to keep the volume of your computer the same!

4) Listen to these two sounds. Of which does the sound wave have a higher amplitude?

Sound A

Sound B

• Make sure to be in presentation mode.
• Click the icon to play the sound.
  
• Make sure to keep the volume of your computer the same!

The soundwaves of sound B have a higher amplitude, because the sound is louder.

5) Which of these two sound waves will produce a louder sound? Explain.

Image 1

Image 2

5) Which of these two sound waves will produce a louder sound? Explain.

Image 1

Image 2

The soundwaves of imag 2, because they have a higher amplitude.

6) Describe what the amplitude of the wave and what the amplitude of a sounds wave says about that sound.

6) Describe what the amplitude of the wave and what the amplitude of a sounds wave says about that sound.

The height of the peak of a wave measured from the center.

6) Describe what the amplitude of the wave and what the amplitude of a sounds wave says about that sound.

The height of the peak of a wave measured from the center.

The loudness of a sound.

6) Describe what the amplitude of the wave and what the amplitude of a sounds wave says about that sound.

The height of the peak of a wave measured from the center.

The maximum displacement of wave compared to it's rest position.

The loudness of a sound.

Bonus

1. What do you think happens to the loudness of a sound when two soundwaves meet?

Interference

Bonus

2. Are sound waves the only form of waves? If not, list other examples of waves. 

Bonus

3. Does the medium (for example air, or water) through which a wave moves move with the wave?