em waves

• Em waves

  transfer energy from a source to an absorber
• what colour of light has the lowest frequency and longest wave length

  red
• what colour of light has a higher frequency and shorter wave length

  violet
• from radio to gamma the frequency

  increases
• the wavelength from radio to gamma

  decreases
• EM waves dont need to travel through a medium
• all EM waves travel at the same speed in a vaccum
• what do radio waves do

  transmit radio and Tv signals
• what is a property of radio waves

  they can travel long distances before being absorbed
• radio waves can deflect off a layer of charged particles in the atmosphere
• what is significant about radio waves bouncing off ionosphere

  allows them to travel long distances around earth
• what are microwaves used for

  heating food and satellite communications
• why do microwaves heat food

  because most food contain water molecules that absorb the energy and causes the temp to increase
• microwaves can pass through the atmosphere without being reflected or refracted
• what is infrared used for

  heating and cooking in ovens and infra red cameras
• infra red is easily absorbed by the surface of an object
• visible light is used for

  communication with fibre optics
• if we transmit pulses of light down fibres then we can carry information
• why can visible light carry a lot of information

  short wavelength
• how is UV used

  energy efficient light bulbs , tanning salons
• how do energy efficient light bulbs work

  the Uv energy is absorbed by the internal surface of the bulb and converted into visible light