Why microwave heats some materials and doesn't do so with others?

Answer 1

Microwaves heat food by exciting water molecules. Anything with watermolecules will get hot plate for example or food

Answer 2

Microwave only heats water. It causes the negative and positive sides of the molecules of water to rotate and hit against each other causing heat. Microwaves are tuned to only cause water to heat up. Since most all things have some water in them, it will heat up just about all foods (even saltine crackers are 10% water). Some things like metal and foil will actually reflect the microwave power causing dangerous sparks and even a fire. So stick to the oven for jiffy pop popcorn.

C

Answer 3

It depends on the specific frequency of the microwaves. In the microwave ovens commonly marketed, the frequency is set so that it excites water molecules more than anything else. So if something you put into the microwave is made of molecules that are about the same size as water molecules (or the substance contains some amount of water), the microwaves will heat it up. However, if you put something in that is made of molecules that are much bigger than water, then the heating effect will be greatly lessened, even negligible.

Answer 4

Microwaves happen to be at the wavelength that vibrates water molecules. Since foods contain water, food in a microwave oven will heat up because the vibrating water molecules are causing friction at a molecular level. If you stick something in a microwave oven that doesn't have any water it won't heat up.

Answer 5

Good question. Because microwaves heat from the inside-out. So, for example, if you microwave a liberal's brain, nothing will happen because there must be something inside to heat.

Answer 6

A microwave oven is simply a radio transmitter whose output is constrained to stay inside a shielded box. Anything which absorbs electromagnetic radiation and has resistance will be heated.

The radio frequency was chosen for greatest efficiency when heating water because that's what's in most food.

Answer 7

Microwaves can supply energy to atoms or molecules whose energy states occur in integral variations of microwave energy. If such materials are exposed to microwave radiations, they heat up, otherwise they do not.

Answer 8

Microwaves heat the water molecules in the food. If the food is dry (like a cracker), it's not going to get very hot in a mircrowave, or at least it won't very fast.

Answer 9

Every type of molecule has certain energy levels of vibration, rotation, and electron energy. The nature of the molecule (especially its geometry) determine the energy levels. A photon that corresponds to a difference in energy levels will excite a molecule in a lower energy level to a higher energy level, and will thereby be absorbed. If the photon does not correspond to a difference in energy levels, it will not be absorbed.

Differences in vibrational and rotational energy levels usually correspond to microwave frequencies. Differences in electron energy levels usually correspond to visible and ultraviolet frequencies.

A microwave produces photons with only one frequency of electromagnetic energy - it is in that way similar to a laser that produces only photons of a single frequency of light energy.

The microwave frequency is chosen to excite water molecules. However, some other organic compounds also may absorb that particular frequency, as they can be very complex molecules with lots of vibrational and rotational modes.

Eventually, the water molecule that is excited to a higher energy level will collide with other molecules and will return to its lower energy level. This takes only microseconds or milliseconds. When it does that, the vibrational/rotational energy is converted to kinetic energy (heat).

Answer 10

interesting ... what did u not managed to heat up using a microwave.