In GCSE Science students will spend some time looking at both electromagnetic and mechanical waves. This is the third of six quizzes on waves and it looks at one particular type of longitudinal wave - sound.
All waves are one of two different types - transverse or longitudinal. When something vibrates, it creates a sound wave. Sound waves are longitudinal waves and the energy they carry causes vibrations in a medium, so they are mechanical waves. Like all mechanical waves, sound waves can only travel in places where there are particles that are sufficienty close to make the next-door particles vibrate. This limits sound to being heard only in solids, liquids and gases. Science fiction films nearly always show sounds in space. This is technically wrong but let's face it, without the sounds these films would be dull and boring!