Wattage: Understanding Output for Wireless Devices

[mjwolf]

microwave wattage...

How is output wattage determined for wireless devices? For example, microwave ovens emit sound waves at similar fequency to wireless devices, yet they cook food. I know my cell phone is at 2.5 ghz, but the wattage output is so low that it supposedly does not affect me. My wireless router at home is at 5GHZ.

Do ovens simply concentrate these microwaves? Is something else going on?

TIA



Mike-

 

[Deeviant]

I'm not am expert but I think I may have something for you.

One thing though, microwaves do not emit sound waves as their mechanic for heating things up, they emit electromagnetic waves.

A microwave does concentrate the energy(it is contained within the heating area), it also has a much more powerful electromentic wave generator(in this case a magnetron) that, although produces the same frquency electromagnetic energy as your phone, it emits far greater quantities of it.

 

[russ_watters]

Originally posted by mjwolf
How is output wattage determined for wireless devices? For example, microwave ovens emit sound waves at similar fequency to wireless devices, yet they cook food. I know my cell phone is at 2.5 ghz, but the wattage output is so low that it supposedly does not affect me. My wireless router at home is at 5GHZ.

Do ovens simply concentrate these microwaves? Is something else going on?

None of those are sound waves. They are electromagnetic: like radio or light.

Power output and frequency are related only insofar as each individual photon has a specific energy level. A microwave produces 1000w or so while a cell phone a couple of miliwatts quite simply because that's what they were designed to do.

 

[Nereid]

... and a microwave heats food because ...

What is the atomic/molecular-level mechanism by which the microwaves get turned into increased vibrational (rotational?) motion of the atoms/molecules? In what way is a microwave oven more 'efficient' than a grill, or a convection oven, or a saucepan on a gas fire? Does the frequency at which the microwave oven works make much difference (to the heating efficiency)?

 

[motai]

Originally posted by Nereid
What is the atomic/molecular-level mechanism by which the microwaves get turned into increased vibrational (rotational?) motion of the atoms/molecules? In what way is a microwave oven more 'efficient' than a grill, or a convection oven, or a saucepan on a gas fire? Does the frequency at which the microwave oven works make much difference (to the heating efficiency)?

From what I know of microwaves (not much), the microwaves themselves stimulate the water molecules in the food, like boiling water on an oven. The reason higher-frequency waves (like gamma, x-ray) do not do the same effect is because they simply punch through the food and don't stimulate the water molecules. I may be misconcieved though, food cooking is not really my expertise (though I can stir-fry).