waves

• what is the frequency?

  the number of complete waves that pass a point per second, measured in hertz (Hz)
• the higher the frequency the higher the what?

  pitch and the smaller the wavelength
• what is the amplitude?

  the distance from the middle of a wave to its peak, it is also proportional to the loudness of a sound
• what is the human range of hearing?


  20-20,000Hz
• which colour of visible light has the highest frequency?

  violet
• which colour of visible light has the lowest frequency?

  red
• what do we call light just beyond the red end of the spectrum?

  infrared
• what do we call light just beyond the violet

  end of the spectrum?

  ultra violet
• what are the parts of the electromagnetic spectrum?


  radio waves, microwaves, infrared radiation, visible light, ultra violet, x-rays, gamma rays
• give uses for all parts of the electromagnetic spectrum

  • radio waves - communications
  • microwaves - heating food quickly
  • infrared - thermal imaging/ TV remotes
  • visible light - seeing/colours
  • ultra violet - tanning/kills viruses
  • X-rays - medical scans
  • gamma rays - kills cancer cells
• what is wave speed?

  the distance a wave travels in one second. it is measured in m/s
• what is the equation for wave speed?

  V = fλ

  v = wave speed (m/s)

  f = frequency (Hz)

  λ = wavelength (m)
• eg. a wave travels at 40m/s. if its wavelength is 0.2m, what is its frequency?


  v = fλ, so f = v divided by λ

  40 divided by 0.2

  = 200Hz
• what is the multiplier and symbol for kilo

  multiplier = $X10^3$

  symbol = K
• what is the multiplier and symbol for mlli?

  multiplier= $X10^-3$

  symbol = m
• REFLECTION

  fill in the gaps

  the wave is incident on a surface

  it bounces off objects

  the angle of incidence is equal to the angle of reflection
• give 2 examples of reflection

  echo, mirror
• REFRACTION

  fill in the blanks

  The wave is incident on a change in medium

  this causes a change in speed

  if the wave slows down it bends towards the normal

  if the wave speeds up, it bends away from the normal
• give 2 examples of refraction

  light bending in water, sound travelling further at night
• REFRACTION

  I > r
• DIFFRACTION

  fill in the blanks

  Diffraction occurs when a wave passes through a gap of similar size to its wavelenth

  the wave spreads out in a circular pattern
• give two examples of diffraction

  classroom doors and sound, radio waves around hills
• REFLECTION

  I = r
• What is a longitudinal wave?


  When the direction of oscillation is parallel to the direction of travel
• give examples of longitudinal waves


  sound waves, seismic p waves
• what are transverse waves?


  When the direction of oscillation is perpendicular to the direction of travel
• give examples of transverse waves


  electromagnetic waves, water, seismic S waves
• what is time-period?


  the time it takes for one wave to pass a point
• what is the equation for time period?

  $F=$$1/t$

  f = frequency (Hz)

  t = time period (s)
• A wave completes one oscillation every 0.4s calculate the frequency of the wave

  F = 1/t = 1/0.4 = 2.5Hz