Radiation

• What does every object do with EM radiation?

  Every object absorbs and emits EM radiation
• How does radiation affect the Earth's temperature?

  Radiation influences the Earth's temperature
• Which surfaces are better emitters of radiation?

  Black surfaces are better emitters
• What is the relationship between radiation and temperature?

  • Radiation affects temperature
  • Black surfaces emit more radiation
  • White surfaces emit less radiation
• What is the peak wavelength of light from the Sun?

  About 500 nm
• Which star is cooler if one has a peak wavelength of 500 nm and another 850 nm?

  The star with 850 nm is cooler
• What are carrier waves used for?

  • To carry any type of signal
  • Essential for communication
• How is the radio and microwave spectrum divided?

  Into different bands for communication purposes
• What happens to information as wavelength decreases?

  More information is carried
• What is the range of shorter wavelength waves compared to longer ones?

  Shorter wavelength waves have a shorter range
• What are microwaves used for?

  Satellite phone and TV signals
• What do some scientists think about mobile phone radiation?

  It may affect the brain, especially in children
• Why are optical fibres useful in communications?

  They carry more information than radio waves
• What type of radiation do optical fibres carry?

  Visible light or infrared radiation
• How do optical fibres provide security in communication?

  Waves stay in the fibre, reducing interception
• What produces an audio signal in a radio station?

  A microphone produces an audio signal
• What does the audio signal modulate in a radio station?

  Carrier waves' frequency
• What happens when radio waves are absorbed by a receiver aerial?

  They induce an alternating current
• What does the receiver circuit do with the audio signal?

  It separates the audio signal from carrier waves
• What does the loudspeaker do in a radio station?

  It emits sound waves