p5.1 wave behaviour

• what is amplitude?

  the distances from the undisturbed position to the peak/trough of a wave

  is measured in metres

  it has the symbol A
• what is wavelength?

  the distances between one point on the wave to the same point on the next wave

  --> from one peak to the next peak

  it is given the symbol λ(lambda)

  it is measured in metres
• a diagram showing the amplitude and wavelength of wave

  A) wavelength

  B) amplitude

  
• what is frequency?

  the number of waves passing a point in a second

  it is given the symbol f and is measured in Hertz
• what is a time period?

  the time taken for a single wave to pass a point

  it is measured in seconds

  it is given the symbol T
• write the equation that links frequency and time period

  frequency = 1/time period
• what is wave speed?

  the distance travelled by a wive each second

  it has the symbol v

  it is measured in metres per second

  wave speed is the speed at which energy is transferred through a medium
• how to calculate wavespeed?

  frequency x wavelength
• what are waves?

  repeated vibrations that transfer energy
• what are the two types of waves?

  transverse and longitudinal
• transverse waves are defined as waves where the points along their length vibrate at 90 degrees to the direction of energy transfer
• features of a transverse wave:

  • energy transfer is perpendicular to wave motion
  • they transfer energy but not matter
  • they can move in solids and on the surfaces of liquids but not inside liquids or gases
  • EM waves can move in solids, liquids and gases as well as in vacuums
• diagram of a transverse wave:

  A) wave peak

  B) wave trough

  C) 90 degrees

  
• what type of wave are sound waves?

  longitudinal
• how to calculate the speed of sound?

  distance travelled by sound / time taken
• how to measure sound between 2 points:

  1. two people stand a distance of around 100m apart
  2. distance measured between them using a trundle wheel
  3. one person has 2 wooden blocks, that they bang together above their head
  4. second person has a stopwatch which they start when they see the first person banging the blocks together and stop when they hear the sound
  5. repeat several times
  6. take an average value for the time
  7. use the equation to find the speed of sound
• how to measure wave speed in water:

  1. choose a calm/flat water surface such as a lake or a swimming pool
  2. two people stand a few metres apart using a tape measure
  3. one person counts down from 3 and then disturbs water surface to create a ripple
  4. second person starts a stopwatch to time how long it takes for the first ripple to get to them
  5. repeat 10 times
  6. find an average time
  7. use equation "speed = distance moved / time taken " to calculate wave speed
• how do sound waves transfer energy?

  by the molecules vibrating and knocking into neighbouring molecules
• (sound waves)

  the more molecules that are present, the faster the wave can transfer energy.

  THEREFORE:

  • sound waves travel fastest in solids
  • sound waves travel slowest in gases
• where do sound waves travel the fastest?

  solids
• where do sound waves travel the slowest?

  gases
• when sound moves from a denser medium to a less dense medium:

  • the wavelength of the sound wave decreases
  • the frequency of the sound wave stays the same
  • the velocity of the sound wave decreases
• what 3 things happen to the sound wave when sound moves from a denser medium to a less dense medium?

  1. wave length decreases
  2. frequency stays the same
  3. velocity decreases
• what 3 things happen to the sound wave when sound moves from a less dense medium to a denser one?

  1. wavelength increases
  2. frequency stays the same
  3. velocity increases