Microwaves + Infrared radiation

what are the two types of microwaves

1. microwaves that aren't absorbed by water molecules

2. microwaves that are absorbed by water molecules

how and why are microwaves that aren't absorbed by water molecules used in communications

used for communication using satelites as they have to pass through the earth's atmosphere which contains a lot of water vapour

how it works is that once the microwaves make it through they are received by a satlelite then transmitted back down to earth where we can detect them using a satelite dish

how are microwaves that are absorbed by water molecules used in heating our food in microwave ovens

most of the food we eat contains lots of water molecules, when microwaves are fired at our food, the energy from the waves gets absorbed by all the water molecules and as the water molecules vibrate more due to all the new energy, they transfer energy to neighbouring particles and so it spreads through the food via conduction and convection

what are the dangers of microwaves

if exposed to it for too long it can cause heating of body tissues

what are the dangers of infrared radiation

can be absorbed into the skin and cause skin burns

infrared radiation is emitted from all objects that have ________ energy

thermal

What are the uses of infrared radiation?

electrical heaters, cooking food, infrared cameras

how is IR used in cooking?

heating metals eg. ovens and grills to very high temperatures emits lots of IR so it heats our food by transferring the heat energy ( however it doesn't penetrate the surface of the food unlike microwaves)

how is IR used in electric heaters?

uses electrical energy to heat the metal; because it's so hot the heater emits IR to the surroundings