Microwaves & Infrared

• What are the second and third groups in the electromagnetic spectrum?

  Microwave radiation and infrared radiation
• Why do microwaves have relatively long wavelengths and low frequencies?

  Because they are on the far left of the spectrum
• How can microwaves be split into two groups?

  • Microwaves not absorbed by water molecules
  • Microwaves absorbed by water molecules
• What is the use of microwaves that aren't absorbed by water molecules?

  Communication using satellites
• Why can microwaves pass through the Earth's atmosphere?

  They aren't absorbed by water molecules
• How are microwaves received by satellites?

  They pass through the atmosphere and are detected
• What do we use to detect microwaves transmitted from satellites?

  Satellite dish
• How do microwaves heat food in microwave ovens?

  They are absorbed by water molecules in food
• Why do foods with more water heat up more quickly in microwaves?

  Water molecules absorb more microwave energy
• What is infrared radiation emitted from?

  All objects with thermal energy
• How does the amount of infrared radiation emitted relate to an object's temperature?

  The hotter the object, the more it emits
• What is one use of infrared radiation?

  Infrared cameras to see in the dark
• How do infrared cameras help spot living organisms?

  By detecting emitted infrared radiation
• Why do warm animals appear bright in infrared images?

  They emit lots of infrared radiation
• How does infrared radiation cook food differently than microwaves?

  It doesn't penetrate the surface of food
• What happens to metal when heated to high temperatures in ovens?

  It emits lots of infrared radiation
• How do electric heaters use infrared radiation?

  They heat metal which emits infrared radiation
• When are microwaves and infrared waves harmful?

  In high quantities
• What happens to living cells in a microwave?

  They boil and are destroyed
• What can happen if you put your hand too close to a grill?

  You could get burns
• What are the main uses of microwaves and infrared radiation?

  Microwaves:

  • Communication via satellites
  • Heating food in microwave ovens

  
  

  Infrared Radiation:

  • Night vision with infrared cameras
  • Cooking with ovens and grills
  • Heating rooms with electric heaters