• Understand that sound waves are produced by vibrating objects, and that sound requires a medium to travel through. • Understand the links between amplitude, loudness and energy in a sound wave. • Understand the links between wavelength, frequency and pitch of a sound. Textbook references: p. 128-129, p. 132-133 Filepath: I:\Ph\Y11\11.2 Physics - Mr Peter (PEW)\11.2 Lesson Notes\ Waves Topic\Lesson 3 - The Nature of Sound Sound: Learning Objectives
Transcript
• Understand that sound waves are produced by vibrating objects, and that sound requires a medium to travel through.
• Understand the links between amplitude, loudness and energy in a sound wave.
• Understand the links between wavelength, frequency and pitch of a sound.
Textbook references: p. 128-129, p. 132-133
Filepath: I:\Ph\Y11\11.2 Physics - Mr Peter (PEW)\11.2 Lesson Notes\Waves Topic\Lesson 3 - The Nature of Sound
Sound: Learning Objectives
Waves: Sound
Contents
Sound as vibrations
Describing sound waves
Sound waves need a medium
How do instruments produce sounds…
What do you have to do to musical instruments to get sounds from them?
How do you change the pitch and loudness for each one?
violin strings
drum skin
voice box
trumpet
What causes sound?
Sounds are made when an object vibrates.
If you take a tuning fork and strike it against a block of wood, the tuning fork vibrates and you hear a sound.
How does sound travel?
How does sound reach your ear?
When the drum skin is struck, it ****** which causes the air beside the drum to vibrate.
The compression and stretching of air ****** creates a sound wave which is carried through the air to your ear.
What type of wave is a sound wave?
****** wave
Waves: Sound
Contents
Sound as vibrations
Describing sound waves
Sound waves need a medium
Remove the air from the bell jar and what happens to the sound?
The bell-jar experiment
Place a ringing clock inside the bell jar and what happens?
There is air inside the bell jar so the sound can travel and be heard.
With a ****** inside the bell jar, the sound cannot be heard. Why?
vacuum pump on
Sound and states of matter
Sound waves need a substance to travel through.
What are all substances made of?
What is the particle model of a solid, a liquid and a gas?
In which state are the particles closest together?
In which state are the particles furthest apart?
******
******
******
solid gasliquid
Sound and states of matter
Sound waves travel by particles vibrating.
What state does sound travel fastest through and why?
The particles in a solid are closer together than in a gas or a liquid. This means ****** are more easily passed from particle to particle and so sound waves travels faster.
solid gasliquid
Sound waves travel fastest through ****** .
Understanding Review Questions
1. Describe briefly how you would increase the loudness and the pitch of:- a stringed instrument (such as a guitar)- a wind instrument (such as a flute)- a percussion instrument (such as a drum)
2. An unmanned boat explodes loudly while at sea. Can you explain why a dolphin (underwater) 2km away reacts to the sound waves faster than a sailor on the deck of a boat the same distance away?
Waves: Sound
Contents
Sound as vibrations
Describing sound waves
Sound waves need a medium
Sound waves can be studied with this type of equipment.
******
signal generator
oscilloscope
Which piece of equipment…
• produces signals over a range of frequencies and of varying amplitudes?
• converts signals into sound waves?
• is used to study the frequency and loudness of a sound?
****** generator
******
loudspeaker
Studying sound waves
loud soundquiet sound
What is the difference between the sound wave of a quiet sound and a loud sound?
The loud sound has taller waves.
What would the sound wave of a very loud sound look like?
The louder the sound, the greater the ****** .
Why sound is quiet or loud?
Which is the loudest?
Sound ****** is the loudest.
Which trace represents the loudest sound?
Sound A has the ****** amplitude, which means the wave has ****** energy and so the sound is ****** .
A B
low pitch sound high pitch sound
What is the difference between the sound wave of a low pitch sound and a high pitch sound?
The ****** ****** sound has a ****** wavelength, so more waves are visible. It has ****** frequency waves.
What would the sound wave of a very low sound look like?
Why sound is low pitch or high pitch?
Which is the highest?
Which trace represents the sound with the highest pitch?
Sound B is the ****** pitched.
Sound B has the ****** wavelength and the ****** number of waves visible, so it has the ****** frequency.
BA
Wave animation
• Understand that sound waves are produced by ****** objects, and that sound requires a medium to travel through.
• Understand the links between amplitude, loudness and ****** in a sound wave.
• Understand the links between wavelength, frequency and ****** of a sound.
