120 likes | 548 Views
Waves. What are waves?. There are many different kinds of wave: Light waves Sound waves Waves on water Seismic waves Waves along a rope, or a slinky. There are two sorts of waves. Transverse waves Longitudinal waves. Transverse waves. Most waves are transverse
E N D
What are waves? • There are many different kinds of wave: • Light waves • Sound waves • Waves on water • Seismic waves • Waves along a rope, or a slinky
There are two sorts of waves • Transverse waves • Longitudinal waves
Transverse waves • Most waves are transverse • The vibrations in transverse waves go from side to side • The energy is travelling in one direction, with the vibrations moving at a 90o angle to the direction the wave is travelling
Transverse Waves After a great performance at a drum and bugle corps contest, the audience decides to start a wave in the stands. Each person rises and sits at just the right time so it looks like a wave. This is a transverse wave because, as the wave moves across the stands, folks are moving up and down. wave direction
Longitudinal Waves • Longitudinal waves have vibrations moving in the same direction that the wave is travelling in • Examples of longitudinal waves are: Sound waves (in solids, liquids and gases) Shock waves (e.g. seismic waves ) A slinky (when plucked)
Ouch! Longitinal Waves (cont.) C = Compression (high kid density) R = Rarefaction (low kid density) The compression (the pulse) moves up the line, but each kid keeps his place in line. C Ouch! R C Ouch! C R
Examples of different waves Transverse waves: • All electromagnetic radiation, e.g. light • Ripples on water • Waves on strings • A slinky that is waved up and down Longitudinal waves: • Sound • Shock waves • A slinky when plucked
What do waves do? All waves carry energy
What sort of energy is being carried? • Heat energy is carried by light, infra red and microwaves • X-rays and gamma rays carry energy which can damage cells • Sounds carry energy in the form of vibrations. Loud sounds can make an object vibrate (move) • Waves on water can move things, and can even be used to generate electrical energy • Televisions, radios, fibre optics and speech are all ways in which energy travels (and also information)
What does a wave look like? A wave can be drawn as a wavy line:
What are the main parts of a wave? • Wavelength () • Amplitude • Frequency (f) • This is the distance from the crest of one wave to the crest of the next wave • This is the height of a wave from the mid-point (where there is no displacement) to a peak • This is the number of complete waves per second, passing a certain point. It is measured in Hertz (Hz)