TRANSVERSE WAVE eg light Direction of wave Particle motion Particles move to and fro at 90 0 to the direction of the wave in a transverse wave. LONGITUDINAL WAVE eg sound Direction of wave Particle motion Particles move to and fro in the direction of the wave in a longitudinal wave.
Frequency The frequency of a wave is the number of waves generated by a source in a second. –The symbol for frequency is f –Its unit is Hertz (Hz) or cycles per second Amplitude Amplitude is the maximum displacement of a particle from its mean position –The symbol for amplitude is A –It is measured in metres (m)
With sound when travelling within a medium, the wave speed is constant, and independent of wave frequency. What will the time delay in hearing the sound from a brass band for an observer standing 660 m away? Assume the light arrives instantaneously and sound travels at 330 m/s. Speeds of waves
Wavelength The distance between each cycle of the wave is called the wavelength. Particles in phase –Particles travelling at the same speed in the same direction are said to be in phase The wavelength of a wave is the distance between two successive points in phase. Direction of wave
Wavelength is given the Greek symbol lambda Wavelength is a distance, measured in m PERIOD The period of a wave is the time taken for one wave to pass a given point. Period is given the symbol T It is measured in s
The frequency of a wave is the number of waves passing a point per second. Its unit is Hertz (Hz) or cycles per second. The wavelength is distance between each cycle of the wave (the distance between consecutive crests) If 2 pass each second its frequency is 2 Hertz If the wavelength is 30 cm Wave speed = frequency x wavelength Then the velocity of the wave is 2 x 30 = 60 cm/s The wave speed or velocity is how fast the wave is travelling. http://www.crocodile- clips.com/absorb/AP4/sa mple/DJFPh065.html
THE WAVE EQUATION Where v = wave speed f = frequency = wavelength P 669-671
The electromagnetic spectrum consists of transverse electric and magnetic fields varying at right angles to each other. The entire pattern moves in a direction perpendicular to both E and B fields.
7.5 x 10 -7 m4 x 10 -7 m6.0 x 10 -7 m5.0 x 10 -7 m7.0 x 10 -7 m
Properties of all electromagnetic waves 1.They transfer energy from one place to another 2.They are all transverse waves 3.They can be reflected, refracted, diffracted 4.They can all travel through a vacuum 5.They all travel at 3.00 x 10 8 m/s in a vacuum 6.The shorter the wavelength (the higher the frequency), the more penetrating they become and the more dangerous they are