Year 11 Physics: the World Communicates Dot Points

Topics: Light, Electromagnetic radiation, Wavelength Pages: 9 (2474 words) Published: November 14, 2012
The World Communicates
1.The wave model can be used to explain how current technologies transfer information * describe the energy transformations required in one of the following: mobile telephone, fax/ modem, radio and television Energy transmission in mobile telephone:

sound wave energy (input sound) -> electrical (in transmitting phone) – > radio wave (transmit signal) -> electrical (in receiving phone) -> sound (output sound) * describe waves as a transfer of energy disturbance that may occur in one, two or three dimensions, depending on the nature of the wave and the medium A wave is a travelling disturbance which transfers energy without transporting matter. They may occur in 1D, 2D or 3D, depending on the nature of the wave and the medium. 1D- slinky, laser light >>> only moves in one direction 2D- water wave >>> propagates in all directions on a single plane 3D-light, sound, all EM waves >>> spreads/ radiates in all directions from a single point * identify that mechanical waves require a medium for propagation while electromagnetic waves do not Mechanical waves require a medium (particles in order to propagate) while electromagnetic waves do not. Classification of Waves:

-in terms of medium > mechanical (requires), electromagnetic (doesn’t require) -in terms of particle oscillation > mechanical >>> transverse (perpendicular), longitudinal (parallel) * define and apply the following terms to the wave model: medium, displacement, amplitude, period, compression, rarefaction, crest, trough, transverse waves, longitudinal waves, frequency, wavelength, velocity Mechanical Waves

-require a medium to propagate
-involves the transfer of energy through a medium by the motion of particles of the medium itself -particles moves as oscillations or vibrations around a fixed point

Transverse waves (e.g. light)
- mechanical waves
- particles of the medium oscillate back and forth in a direction perpendicular to the direction of wave propagation -does not require a medium
Longitudinal/compressional waves (e.g. sound)
-mechanical waves
-particles of the medium oscillate back and forth in a direction parallel to the direction of propagation -requires a medium
Period (T)
– time taken for a single wave to pass through a fixed point OR the time taken for a particle of a medium to make one complete oscillation (measured in seconds) -T = 1f
Frequency (f) – number of waves that pass through a fixed point per second OR number of complete oscillations of a medium particle in one second (measured in hertz > Hz) Medium – material through which a wave can propagate

Displacement-shortest distance from initial position to final position of a particle Amplitude (A) – maximum displacement of particles from the undisturbed state (equilibrium position) Compression – zones where particles are closer together than in their undisturbed state Rarefaction – zones where the particles are further apart than in their undisturbed state Crest- highest part of the waves

Trough- lowest part of the wave
Wavelength (λ) – distance between 2 successive identical points on a wave (e.g. distance measured in metres, between adjacent crests or troughs) Velocity (v) – speed at which the wave transfers energy away from the source

* describe the relationship between particle motion and the direction of energy propagation in transverse and longitudinal waves Particles in a transverse wave oscillate back and forth in direction perpendicular to direction of propagation. Particles in a longitudinal wave oscillate back and forth in direction parallel to direction of propagation. * quantify the relationship between velocity, frequency and wavelength for a wave:

Velocity is directly proportional to the product of the frequency and wavelength of the wave. 2.Features of a wave model can be used to account for the properties of sound * identify that sound waves are...
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