3 Sound Flashcards
What kind of waves are sound waves?
Longitudinal waves.
What can these waves do?
They can be reflected and refracted.
How are sounds produced?
By objects that are vibrating.
How do we hear sounds?
When these vibrations, travelling as sound waves, meet our ears.
What happens if a sound wave strikes a surface?
It may be reflected.
How are sound waves reflected?
They are reflected so that the angle of incidence is equal to the angle of reflection.
How do ships find out the depth of the water beneath them?
Using sonar, which uses the idea of reflecting sound waves.
What are the steps for sonar to take place?
1) Sound waves are emitted from the ship and travel to the seabed (seafloor).
2) Some of these waves are reflected from the seabed back up to the ship.
3) Equipment on the ship detects these sound waves.
4) The time it takes the waves to make this journey is measured.
5) Knowing this time, the depth of the sea below the ship can be calculated.
How can sound waves be refracted?
If some parts of a sound wave are travelling through warm air, they will travel more quickly than those parts travelling through cooler air. As a result the direction of the sound wave will change. It will be refracted.
How can we tell that sound waves are refracted?
Standing at the edge of a large pond or lake we can sometimes hear sounds from things on the other side of the water much more clearly than we would expect. This is due to refraction.
What is a picture that shows why sometimes sounds travelling across water are louder than we expect?
What is an explanation of the picture that shows why sometimes sounds travelling across water are louder than we expect?
1) Most of the sounds we hear travels to us in a straight line (Path B).
2) But some sounds travel upwards (Path A).
3) If the temperature conditions are right, then as the sound waves travel through the air they are refracted and follow a curved path downwards (Path C).
4) We now receive two sets of sound waves.
5) So the sound we hear seems louder and clearer.
What kind of sounds do larger amplitudes represent?
Loud sounds.
What kind of sounds to smaller amplitudes represent?
Quiet sounds.
