P13

• How many types of electromagnetic waves are there?

  Seven types
• What does the electromagnetic spectrum extend from?

  Long wavelength radio waves to gamma rays
• What are the properties of electromagnetic waves?

  Can be reflected, refracted, or diffracted
• What do electromagnetic waves transfer?

  Energy from one place to another
• Can electromagnetic waves travel through a vacuum?

  Yes
• What is the speed of light in a vacuum?

  300,000,000 m/s
• What do electromagnetic waves consist of?

  Oscillating electric and magnetic fields
• What are the uses of different types of electromagnetic waves?

  • Radio: Communication (Radio and TV)
  • Microwaves: Communication (Mobile phones), Cooking
  • Infrared: Security monitors, heat lamps
  • Visible: Photography
  • Ultra Violet: Sun lamps, UV lights
  • X Rays: Medical imaging
  • Gamma: Radiotherapy
• What happens to wavelength as frequency increases?

  Wavelength must decrease
• What is the approximate speed of electromagnetic waves in a vacuum?

  300,000,000 m/s
• What is the relationship between frequency and wavelength in electromagnetic waves?

  As frequency increases, wavelength decreases
• What are the key characteristics of electromagnetic waves?

  • Can be reflected, refracted, or diffracted
  • Are transverse waves
  • Transfer energy
  • Can travel through a vacuum
  • Travel at the same speed
  • Consist of oscillating electric and magnetic fields
• What is the wave equation for electromagnetic waves?

  Wave speed, v = frequency, f × wavelength, λ
• What are the two main types of aerials mentioned?

  Transmitting aerial and receiving aerial
• Why are radio waves emitted by a transmitting aerial?

  Electrons vibrate in the transmitting aerial
• Where are transmitters usually housed?

  On towers and high plots of land
• What happens when radio waves reach a receiving aerial?

  Electrons in the aerial vibrate with the signal's frequency
• What are radio waves primarily used for?

  Broadcasting and communication purposes
• What do vibrating electrons produce in a receiving aerial?

  A small voltage converted into a signal
• How do light waves compare to radio waves in terms of frequency?

  Light waves have a higher frequency than radio waves
• What are optical fibres used for?

  Telecommunications, sensors, and endoscopes
• How is light transmitted along optical fibres?

  By repeated total internal reflection
• What condition must be met for total internal reflection to occur?

  Light hits the wall at an angle greater than the critical angle
• What is the advantage of using light over radio waves for communication?

  Light can carry more information
• Why is communication via optical fibres considered more secure?

  Light cannot escape or get lost in the fibre
• What happens to the light signal in optical fibres over distance?

  It loses energy slowly but can be boosted
• What enables worldwide internet communications through optical fibres?

  Direct connections boosted at repeating stations
• How do astronomers use radio waves?

  To detect radio waves from stars and planets
• What is SETI?

  Search for Extra Terrestrial Intelligence
• How long have radio communications been beamed into space?

  About 100 years
• What is the implication of radio communications fading from space?

  Aliens may detect fewer signals from Earth
• What is replacing radio wave communication for direct communication with satellites?

  Microwaves and light beams in optical fibres
• What will happen to Earth's radio communication signals over time?

  They will gradually fade from spacewaves
• Where does UV light lie in the electromagnetic spectrum?

  Between visible light and X-rays
• How do UV wavelengths compare to visible light?

  UV has shorter wavelengths and higher frequency
• What is the energy comparison between UV light and visible light?

  UV light carries more energy than visible light
• What are some uses of UV light?

  Making inks glow and security detection
• What are X-rays characterized by?

  High energy, high frequency, and short wavelength
• How are X-rays produced?

  When high-speed electrons are stopped by dense materials
• What can X-rays be used to create images of?

  Internal structures in metals, crystals, and bones