Microwaves and infrared radiation

• 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 categorized?

  • 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 microwaves help us do in microwave ovens?

  Heat up our food
• Why do foods with more water heat up more quickly in microwaves?

  Water molecules absorb energy and vibrate
• What is infrared radiation emitted from?

  All objects with thermal energy
• What determines the amount of infrared radiation emitted by an object?

  The object's temperature
• How do infrared cameras help us see in the dark?

  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 when metal is heated to high temperatures in cooking?

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

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

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

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

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

  • Infrared cameras for night vision
  • Cooking with ovens and grills
  • Heating rooms with electric heaters