today's video is focused on microwave radiation and infrared radiation which are the second and third groups in our electromagnetic spectrum and because they're both on the far left of the spectrum they're both going to have relatively long wavelengths and low frequencies if we start with microwaves we can loosely split them into two different groups those that aren't absorbed by water molecules and those that are absorbed by water molecules the ones that aren't absorbed by water molecules are used for communication using satellites because satellites are so far above the earth the microwaves have to pass through the earth's atmosphere which they wouldn't be able to do if they were absorbed by water molecules because our atmosphere contains a lot of water once the microbes make it through they are received by a satellite and then they're transmitted back down to earth where we can detect them using a satellite dish to get things like satellite tv the second type of microwaves are used in microwave ovens where they help us to heat up our food because most of the food that we eat contains lots of water molecules when microwaves are fired at our food the energy from those waves gets absorbed by all the water molecules and as the water molecules start to vibrate more with all that new energy they transfer some of the energy to neighboring molecules so that it spreads throughout the food by conduction or convection this is why foods that contain more water tend to heat up more quickly in the microwave next up we have infrared radiation infrared or ir radiation is emitted from all objects that have thermal energy or heat energy with the amount that gets emitted depending on the object's temperature so the hotter the object the more infrared radiation it will emit one use of this is in infrared cameras that help us to see in the dark and in particular to help us spot living organisms by using a special camera that can detect infrared radiation we can see which areas are hot and which areas are cold by measuring how much infrared radiation they emit and so animals which are fairly warm will appear quite bright because they emit lots of infrared radiation whereas their surroundings which are much cooler will appear darker because they don't emit as much radiation another use is in cooking by heating metal to very high temperatures like in ovens and grills we can make the metal emit lots of infrared radiation which can then heat our food by transferring the heat energy causing it to cook unlike in microwaves though infrared radiation doesn't penetrate the surface of the food which is why bread toasts in a toaster rather than just getting generally warmer like it would in a microwave we also make use of infrared radiation whenever we use electric heaters these devices use electrical energy to heat up the metal of the heater and then because it's so hot it emits infrared radiation to the surroundings which is able to heat up our rooms the last thing we need to say is that microwaves and infrared waves are only harmful to us in high quantities the background radiation that we receive from our surroundings doesn't really do us any harm but if you put living cells in a microwave then they'd boil and be destroyed and if you put your hand in a toaster or too close to a grill then you'd probably get burns as all of your nearby skin cells would get destroyed anyways that's everything for this video so hope you enjoyed it and found it useful and cheers for watching