waves

• What is the formula for period?

  $p =$$1/frequency$
• What is a transverse wave?

  • when the oscillation is perpendicular to the direction of energy travel
• What is a longitudinal wave?

  • when the oscillation is in the same direction as the direction of energy travel
• Examples of longitudinal waves?

  • sound waves
  • ultrasound waves
  • seismic P-waves
• Examples of tranverse waves?

  • ripples on the surface of water
  • vibrations in a guitar string
  • a Mexican wave in a sports stadium
  • electromagnetic waves - eg light waves, microwaves, radio waves
  • seismic S-waves
• label the wave:

  .

  A) CREST

  B) AMPLITUDE

  C) REST POSITION

  D) TROUGH

  E) WAVELENGTH

  F) TIME

  G) DISPLACEMENT

  
• Label the wave:

  .

  A) rarefraction

  B) compression

  C) compression

  D) WAVELENGTH

  
• label the wave:

  .

  A) LONGITUDINAL

  B) ENERGY TRANSFER

  C) VIBRATION

  D) RAREFRACTION

  E) COMPRESSION

  
• what is the frequency of a wave?

  The number of waves passing a point each second
• what is the principle focus?

  Location where parallel rays of light are brought to a focus
• what is the focal length ?

  the length between the lens and the principle focus
• what is a real image?

  A real image is formed when light rays converge and can be projected onto a screen.
• what is a virtual image?

  An image formed by the apparent intersection of light rays, but cannot be projected onto a screen.
• what is the amplitude?

  The maximum displacement of a point on a wave away from its undisturbed position.
• main use of radiowaves?

  • television and radio (including Bluetooth)
• dangers of microwaves?

  • heating of brain(mobile phone use)
• dangers of infrared ?

  • burns
• dangers of ultraviolet

  • skin cancer
  • premature ageing of skin
• dangers of X-rays & Gamma rays?

  • cancer
• uses of microwaves?

  • satellite communications, cooking food
• what is convex lens ?

  • a lens which diverges light rays
• what is concave lens?

  a lens which converges light rays
• what is a black body?

  • a body which absorbs all the radiation incident on it
• uses of infrared

  electrical heaters, cooking food, infrared cameras
• • visible light

  fibre optic communications
• ultraviolet

  • energy efficient lamps, sun tanning
• X-rays

  medical imaging and treatments
• gamma rays

  • for sterilising.
• order of EM waves from low frequency to high

  • radio
  • microwave
  • infrared
  • visible light (red to violet)
  • ultraviolet
  • X-rays
  • gamma rays.
• explain what happens to the ultrasound wave when it reaches the kidney?

  • partial reflection/absorption at front of kidney
  • partial reflection at back of kidney