Amplitude- The height of any wave, be it sound, water or electromagnetic.
Compressions- Areas of high pressure where springs or particles are close together.
Crest- The top of a wave.
Diffraction- waves spread out after passing through a gap.
Electromagnetic waves- these are electric and magnetic waves and do not need particles to pass the energy on.
Frequency- the number of waves produced per second
Hertz (Hz)- the unit used to measure frequency.
Interference- when one wave meets another
Longitudinal waves- the particles oscillate along the direction in which the wave is travelling
Mechanical waves- these waves disturb particles- the particles pass the energy on.
Rarefactions- areas of low pressure where the springs are stretched out.
Reflection- waves bounce back when they hit a solid object.
Refraction- waves change speed and direction if they pass through another substance.
Transverse waves- the particles move at right angles to the waves.
Trough- the bottom of a wave.
Wavelength- the distance from one crest or one trough to the next.
What is sound? * Sound is a type of energy made by compression waves caused by vibrations * When any object vibrates, it causes movement in the air particles * These particles bump into the particles close to them, which makes them vibrate too causing them to bump into more air particles. * This movement, called sound waves, keeps going until they run out of energy. * If your ear is within range of vibrations, you hear the sound. * Picture a stone thrown into a still body of water. The rings of waves expand indefinitely. * The same is true with sound * Irregular repeating sound waves create noise, while regular repeating waves produce musical notes.
22/03/13 * When the vibrations are fast, you hear a high note * When the vibrations are slow, it creates a low note * The sound waves in the diagram show the different frequencies for high and low notes
Travelling sound waves * In general, sound travels fastest through solids, slightly less fast through liquids, and slower through gases. * This is because the particles (atoms or molecules) in a solid are touching each other and rather fixed together. * That is why a solid is “solid”. * Since the particles are bonded together, a sound wave moving one particle immediately transfers the motion (energy) to the one touching it. * A sound wave hitting one is almost immediately transferred to a neighbour. * In a liquid, the particles are touching each other, but they are not fastened to each other quite as strongly as they are in a solid. * Some of sounds energy is wasted pushing the particles around because they can solid past each other. * In a gas, the molecules are rather far apart. * For sound to travel through a gas, the molecules must move quite a distance before they collide with other molecules. * Sound energy cannot move as quickly when the molecules are not in contact with each other.
Sound through a liquid * Can sound travel under the water? * Yes, sound can travel under the water. * It moves four times faster through water than through the air * It can travel such long distances that whales can hear each other when thye are nearly a hundred miles apart.
Sound through a gas
History of speed sound * The speed of sound is the speed that sound waves