Sound
- Created by: emews
- Created on: 05-11-17 15:01
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- Sound
- Sound waves are longitudinal waves which means they vibrate in the same direction as the direction of travel.
- Sound waves can only travel through a solid, liquid or gas medium.
- They travel fastest in solids, then liquids and slowest in gases.
- The sections of the sound waves where the particles are pushed together are areas of compression.
- The sections of the sound waves where the particles are further apart are areas of rarefaction.
- Sound waves can be reflected to form an echo, refracted and diffracted.
- The number of waves per second is measured in Hertz (Hz).
- Sounds in the normal range of human hearing are between about 20 Hz and 20,000 Hz (20 kHz)
- The speed of sound in air is about 340 m/s
- speed = distance / time
- Ultrasound is the name given to sound waves that have frequencies greater than 20,000Hz (20 kHz).
- Computers are able to create detailed images by combining many ultrasound reflection readings.
- Sonar is used on ships and submarines to detect fish, other vessels or the sea bed.
- An oscilloscope is a machine that shows the wave shape of an electrical signal.
- All signals become weaker as they travel long distances. This is called noise.
- Noise affects both analogue and digital signals.
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