uses of EM waves

• What are radio waves classified as?

  Electromagnetic radiation
• What is the wavelength range of radio waves?

  Longer than about 10 cm
• Why can long-wave radio waves be received halfway around the world?

  They diffract around the Earth's surface
• What can long-wave radio wavelengths diffract around?

  Hills and tunnels
• How do short-wave radio signals travel long distances?

  They are reflected from the ionosphere
• What technology uses short-wave radio waves for data transmission?

  Bluetooth
• What is the effect of atmospheric conditions on medium-wave signals?

  They can reflect from the ionosphere
• What is required for TV and FM radio transmissions to work?

  Direct sight of the transmitter
• Why are microwaves used for satellite communication?

  They pass easily through the Earth's atmosphere
• What happens to the signal in satellite communication?

  It is transmitted to and from satellites
• How do microwaves function in microwave ovens?

  They are absorbed by water molecules
• What happens to food in a microwave oven?

  Water molecules heat up and cook food
• What does infrared radiation indicate about an object?

  The hotter the object, the more IR radiation
• What do infrared cameras do?

  Detect infrared radiation and create images
• How does absorbing IR radiation affect objects?

  It causes them to get hotter
• What do electric heaters emit when heated?

  Infrared radiation and visible light
• What determines the properties of EM waves?

  Differences in wavelength, frequency, and energy
• What is the function of optical fibres?

  Transmit data as pulses of visible light
• How do optical fibres work?

  Light is reflected back and forth
• What is fluorescence?

  Ultraviolet light absorbed, visible light emitted
• What is the effect of UV radiation on certain chemicals?

  It causes them to fluoresce
• What gives people a suntan?

  Ultraviolet radiation from the Sun
• What do tanning salons use to give artificial suntans?

  UV lamps
• What is a common use of X-rays in hospitals?

  To take photographs of broken bones
• How do X-rays create images?

  They pass through flesh but not bones
• How are X-rays and gamma rays used in cancer treatment?

  They kill cancer cells with high doses
• What is a medical tracer?

  A gamma-emitting source injected into patients
• Why do radiographers wear lead aprons?

  To minimize exposure to harmful rays
• What type of radiation can be harmful to people?

  X-rays and gamma rays