Waves

• Waves transfer ____from one place to another?

  energy
• What are the oscillations like in a transverse wave?

  perpendicular to direction of energy transfer
• In longitudinal waves what are the oscillation like?

  parallel to direction of energy transfer
• What is a waves frequency?

  number of waves passing a fixed point per second
• What is frequency measured in?

  Hertz (Hz)
• What is the amplitude of a wave?

  maximum displacement that any particle achieves from it undisturbed position (in metres)
• What is a waves wavelength?

  distance from one point on a wave to the equivalent point on the next wave
• What is a waves period?

  time taken for one complete oscillation
• The more energy a wave is carrying the _____ the amplitude?

  higher
• What changes when waves are transmitted from one medium to another?

  speed and wavelength

  NOT frequency
• Doubling the speed, _________ the wavelength?

  doubles

  they are directly proportional
• What can happen to waves at a boundary?

  reflected, transmitted, absorbed, refracted
• angle of incidence = angle of?

  reflection
• What does the direction of refraction depend on?

  the material and the angle at which it hits the boundary
• What is the refractive index?


  the way in which a material affects refraction
• When light travels from a material of low to high refractive index,…..?

  it bends towards the normal
• When light travels from high to low refractive index it…..?

  Bends away from the normal
• Refraction is due to difference in wave…..?

  speed in different materials
• What happens when light enters a medium in which it travels slower and why?

  bends towards the normal:

  1. first part of wave slows down
  2. rest of waves continues at higher speed
  3. waves changes direction
• What is the range of human hearing?

  20 Hz to 20,000 Hz
• How can we hear sounds?

  sound waves cause ear drum to vibrate, vibration heard as sound
• What are examples of sound waves being converted to vibrations?

  in the ear drum, in microphones and glass being shattered by an opera singer
• Ultrasonic waves have a frequency greater than__?__Hz?

  20kHz/ 20,000Hz
• Echosounding is the use of _____ waves for ______objects deep under water and measuring depth of water?

  ultrasonic, detecting
• What is the speed of sound in water?

  1500 m/s
• What are uses of ultrasound?

  pre-natal scanning, detecting faults in materials (without having to cut them), detection of tumours
• P-waves are _____ and S-waves are ____?

  longitudinal, transverse
• Can P or S waves travel through liquids?

  P
• Which are faster P or S waves?

  P waves
• why do seismic waves travel in a curved path?

  Due to earth increasing density with depth
• The shadow zone provides evidence for the _____ of the earths core?

  size
• Are EM waves transverse or longitudinal ?

  transverse
• What are the uses of different EM waves?

  • radio- TV, radio
  • microwaves- satellite communications, cooking food
  • infrared- electric heaters, IR cameras
  • visible light- fibre optic communications
  • UV- sunbeds, security marking
  • X-ray- medical imaging
  • gamma- sterilising food, treatment of tumours
• Changes in ______ and the _______ of atoms results in EM waves.?

  atoms nuclei
• What can UV waves cause the skin to do?

  age prematurely and increase risk of skin cancer
• X-rays and gamma rays are ionising radiation and can damage cells by ionising atoms. what happens if they are absorbed by the nucleus of cells?

  cause gene mutations and cancer
• Do parallel rays of light entering a convex lens converge or diverge?

  converge
• Do parallel rays of light entering a concave lens converge or diverge?

  diverge
• what type of images can concave and convex lenses produce?

  concave- only virtual

  convex-real and virtual
• Can a real image be projected on a screen?

  yes