Waves

• What is a wave?

  A wave is simply a movement of energy.
• How can a Slinky model transverse waves?

  • Move one end of the Slinky up and down
  • The wave travels away from the source
  • Direction of the wave is at right angles to the transfer of energy
• What do transverse waves look like?

  The direction of the wave is at right angles to the transfer of energy.
• How do coils behave in a transverse wave?

  Each coil of the Slinky vibrates up and down.
• How can a Slinky model longitudinal waves?

  • Move one end of the Slinky left and right
  • The wave travels away from the source
  • Direction of the wave is parallel to the transfer of energy
• What do longitudinal waves look like?

  The direction of the wave is parallel to the transfer of energy.
• How do coils behave in a longitudinal wave?

  Each coil of the Slinky vibrates left and right.
• What are examples of transverse waves?

  Water waves and electromagnetic waves, such as light.
• What are the parts of a transverse wave?

  • Peak: high points of the wave
  • Trough: low points of the wave
• What is the wavelength of a wave?

  The wavelength is the distance between two matching points on neighboring waves.
• What symbol is used to represent wavelength?

  The symbol used to represent wavelength is λ.
• What is the amplitude of a wave?

  The amplitude is the maximum distance a point moves from its rest position.
• How is the amplitude of a transverse wave defined?

  The amplitude is the height of a peak or trough from the wave’s rest position.
• What happens to the energy of a wave as its amplitude increases?

  The larger the amplitude, the greater the energy of the wave.
• What are the special names for parts of a longitudinal wave?

  • Compression: sections that are pushed together
  • Rarefaction: sections that are stretched out
• What type of waves are sound waves?

  Sound waves are longitudinal waves.
• What is the frequency range that humans can hear?

  20 Hz to 20 kHz
• How do you calculate the efficiency of a light bulb with an energy input of 100J that gives off 20J as light?

  Efficiency = (Output Energy/Input Energy) * 100 = (20J/100J) * 100 = 20%
• What are P waves?

  P waves are primary waves produced by earthquakes and are longitudinal waves.
• What is the wavelength of a longitudinal wave?

  The wavelength is the distance between two matching points on neighboring waves.
• What is the symbol used to represent wavelength?

  The symbol used to represent wavelength is λ.
• Name four parts of the electromagnetic spectrum.

  Radio waves, microwaves, infrared, visible light
• What are the definitions of key terms related to waves?

  1. Amplitude (a) – height of the wave from the rest position
  2. Wavelength (λ) – distance between two corresponding points on the wave
  3. Frequency (f) – number of waves passing a point in 1 second
• What is infrasound?

  Sound with frequencies less than 20 hertz
• How can we calculate the frequency of waves?

  Frequency = 1 ÷ time period.
• How have seismic waves been used to determine the structure of the Earth?

  By examining how seismic waves travel through different layers
• What is the equation that links wave speed, frequency, and wavelength?

  Wave speed (v) = frequency (f) x wavelength (λ).
• Where do earthquakes start?

  Deep within the Earth's crust, called the focus
• What is the nearest point on the surface to the focus of an earthquake called?

  Epicentre
• If a sound wave travels through water with a wavelength of 2m and a frequency of 100Hz, what is the speed of sound in water?

  The speed of sound in water is $200m/s$.
• What devices are used to detect and record earthquakes?

  Seismometers
• If a wave has a frequency of 350Hz and a wavelength of 4cm, what is the speed of the wave?

  The speed of the wave is $14m/s$.
• What are waves that travel through the Earth called?

  Seismic waves
• What is the velocity of a wave with a wavelength of 50m and a frequency of 30KHz?

  The velocity of the wave is $1500000m/s$.
• What are transverse waves?

  Waves where the displacement is at right angles to the direction of energy transfer
• What are longitudinal waves?

  Waves where the displacement is parallel to the direction of energy transfer
• What are the two types of seismic waves?

  P waves (primary) and S waves (secondary)
• How far does sound travel in 2 seconds if it travels through water at 1500m/s?

  Sound travels $3000m$ in 2 seconds.
• What do P waves do?

  Cause initial tremors and can pass through solids and liquids
• If sound travels through air at 330m/s and Sam hears thunder 5 seconds after seeing lightning, how far away is the storm?

  The storm is $1650m$ away.