Sound and Waves Flashcards
(27 cards)
Sound is a _______________ wave.
Sound is a longitudinal wave.
What is a longitudinal wave?
A wave where the particles move forwards and backwards in the direction that the wave travels.
What is sound measured in?
Decibels (dB)
What is pitch?
The pitch of a sound is how high or low the sound is. A high pitch sound has faster vibrations and higher wave frequency. A low pitch has slower vibrations and a lower wave frequency.
What is frequency?
Frequency is the number vibrations of the wave in one second, also seen as the number of complete waves passing a point in one second.
What is frequency measured in?
Hertz (Hz)
What is the lowest pitch that humans can hear?
20Hz
What is the highest pitch that humans can hear?
20,000Hz
What is a transverse wave?
A wave in which the particles move up and down at right angles to the direction it travels in, like an ocean wave or lifting a rope up and down.
What is amplitude?
The height of the top of a wave from its resting position. The greater the amplitude, the taller the wave (and the louder the sound if a sound wave).
What type of molecules carry sound energy?
Vibrating molecules
Sound needs what to carry it?
A substance
Sound travels faster if the molecules of the medium it is travelling through are what?
Sound travels faster if the molecules of the medium it is travelling through are closer together.
What is a longitudinal wave?
In longitudinal waves, the vibrations are parallel to the direction of wave travel.
Longitudinal waves show areas of compression and rarefaction.
Longitudinal waves are often demonstrated by pushing and pulling a stretched slinky spring.
What are compressions?
Compressions are regions of high pressure due to particles being close together.
What are rarefactions?
Rarefactions are regions of low pressure in longitudinal waves due to particles being spread further apart.
They are the opposite of compressions.
Name two examples of longitudinal waves.
Name any two of:
- sound waves
- ultrasound waves
- seismic P-waves
What is a transverse wave?
In transverse waves, the vibrations are at right angles to the direction of wave travel.
They are often demonstrated by moving a rope rapidly up and down.
Name two examples of transverse waves.
Any two of:
- ripples on the surface of water
- vibrations in a guitar string
- a Mexican wave
- electromagnetic waves (eg light waves & radio waves)
- seismic S-waves
What is the amplitude of a wave?
The amplitude of a wave is the distance from the centre line (or the still position) to the top of a crest or to the bottom of a trough.
What changes the height of the amplitude of a wave?
The volume of the sound.
What is the frequency of a wave?
The frequency of a wave is the number of waves passing a point in a certain time. We normally use a time of one second, so this gives us the frequency hertz (Hz) since one hertz is equal to one wave per second.
What does the frequency of a wave affect?
The frequency of a wave affects the pitch of the sound.
What does the amplitude of a wave affect?
The amplitude of a wave affects the volume of a sound.
