Light & Sound

A form of energy that is caused by vibrations that therefore needs something to travel through. It cant travel through a vacuum

Layers of particles vibrating in turn passing sound energy through the air in rarefractions(spread out) and compressions(compressed together)

• The speed of the vibrations is called the frequency and is measured in herts(H₃). 1 H₃=1 vibration per second
• Musical note A has a frequency of 440 H₃

• Light waves can travel through empty space and therefore dont need a medium to travel through
• Travels best through a vaccum
• Travels at the speed of 300 000 km per second

If light can travel through the substance clearly it is transparent e.g. glass and diamond

If light is scattered as it passes through the substance it is translusent e.g. tissue paper and shower screen

If light is blocked and cannot travel through the substance it is opaque e.g. wood and rock