P1.5- Waves

the nature of the nature of waves

measuring waves

reflection, diffreaction, refraction


musical sound

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  • Created by: gee
  • Created on: 01-05-12 21:21

The Nature Of Waves (P1.5.1)

  • Waves can transfer information and energy


  • vibrations travel at right angles to the direction of energy transfer
  • all electromagnetic waves


  • vibrations travel parrellel to the direction of energy transfer
  • sound waves (and others)
  • rarefractions and compressions

mechanical = need a medium (substance)

electromagnetic = do not need a medium (substance)

                          = can travel through a vacuum

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Measuring Waves (P1.5.2)

amplitude = the distance from the middle (resting point) to the top of a crest

wavelength = the distance from the start of one crest to the start of the next

frequency = the amount of waves which pass through a fixed point every second

Calculating the speed of waves (how much information or energy the wave can carry)

wave speed= frequency x wavelength

     (m/s)             (Hz)               (m)

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Properties: Reflection (P1.5.3)

Laws Of Reflection:

  • normal is perpendicular to the mirror
  • angle of incidence (angle from incident ray to normal)
  • angle of reflection (angle from reflection ray to normal)

angle of incidence = angle of reflection 

real image = image formed by light rays meeting

virtual image = image formed where light rays seem to come from

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Properties: Refraction (P1.5.4)

refraction = changes speed as it crosses the boudary between two substances                             ( between mediums)

                = causing it to change direction

                = all types of waves can refract

DOES NOT occur if waves cross the boudary 90° (normal)

air to glass = angle of refraction is less than the angle of incidence 

glass to air = angle of refraction is more than the angle of incidence

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Properties: Diffraction (P1.5.5)

diffraction = the spreading out of waves when they pass through a gap or around a


  • SMALLER gap means MORE diffraction
  • BIGGER gap means LESS diffraction
  • when the gap is similar to the wavelength, diffraction is at its biggest!


People who live in hilly areas will often get poor reception, because if the radio and microwaves do not diffract enough over the hilly, they will not reach the houses.

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Sound (P1.5.6)

sound waves = longitudinal waves

                      = can not travel through a vacuum

  • something vibrates, causing layers of nearby air to vibrate
  • making layers of air further away vibrate
  • the object continually pushes and pulls creating compressions and rarefractions
  • the waves reach your ears causing ear drums to vibrate
  • allowing you to hear sound

echo = reflection of sound

(has to have bare smooth walls --> fabric = absorbs and uneven = sound scattered)

humans can hear sound at a frequency of 20Hz - 20,000Hz

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Musical Sound (P1.5.7)

high amplitude = louder note

high frequency = higher pitched note

resonates = vibrations inside the instrument build up creating a louder sound

when you play an instrument the instrument (and the air inside) vibrates and creates sound

musical notes = rythmic, waves change smoothly, wave patterns repeat

sound = vary in frequency, no pattern

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Key Words (P1.5)

  • energy                          
  • transverse
  • longitudinal
  • transfer
  • amplitude
  • frequency
  • speed
  • wavelength
  • crest
  • trough
  • vibrations
  • refraction
  • refraction
  • difraction 
  • angle of incidence
  • angle of reflection
  • medium
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