My water service was interrupted the other morning, and I was thirsty, so I took a glass, filled it with ice cubes, and put it in the microwave. I set it for 1 min., it did nothing. I set it for 2 min., it did nothing. What I couldn't understand is that while you could put a cup of water or coffee and set it for 1 min. and have it be boiling hot (even the cup is too hot to touch), the glass of ice (including the glass) is still cold to the touch. I know that if I set it for 4-5 min., it'd melt the ice; I don't understand how it heated liquid so quickly, while not affecting the ice as quickly. I hope that this explains it better. Try it with a glass of ice and check your results.
2007-01-19 00:45:02 · 7 answers · asked by b_masters1 3 in Science & Mathematics ➔ Physics
microwaves work by causing a sort of molecular agitation. heat energy can be defined as the kenetic energy between the atoms. so a hot substances molecules are "vibrating" alot wheras something cold has very little molecular activity. when something is frozen its molecules are locked into place so it's going to require alot more agitation than a substance that has free flowing molecules. if that makes sense. and the glass will remain cold because it has no "free flowing" molecules there all locked very tightly together much like your ice.
2007-01-19 01:02:38 · answer #1 · answered by eskew_obfuscation 3 · 1⤊ 0⤋
microwaves excite molecules to move faster and this generates heat.. so they heat even from the inside for the most part. ice has to absorb a lot of energy to change a form.. between solid/liquid and liquid/gas stages it takes a lot of energy.. so if you give it say 100 calories it would add heat the glass of water... but a cube of ice will heat up to 32f and then absorb much of it to change physical stage but this reduces what is left to raise the temp. higher. sorry i am not good at explaining it but i believe i got the idea across.
2007-01-19 08:56:04 · answer #2 · answered by valiantw2001 2 · 1⤊ 0⤋
Verrrrrry interrresting! I'll be watching the postings for an answer.
Addition: I just tried it. I must have a special microwave. After a minute 22 seconds, I went back to check on my 4 pieces of ice in my glass and it was all water. (warm water)
2007-01-19 08:48:41 · answer #3 · answered by Greywolf 6 · 0⤊ 0⤋
The frequency of a home microwave oven is too high to afffect the ice; it passes right through.
"Bound water and ice have critical frequencies (λS) at about 10 MHz (Ï about 0.1 μ) with raised static dielectric permittivities (εS). At the much higher frequency of microwave ovens such water has a low dielectric permittivity (e.g. ice-1h, εâ = 3.1; cf. ice-1h, εS = 97.5 [94]; εS water (0°C) = 87.9), and is almost transparent, absorbing little energy. This is particularly noticed on thawing where the thawed material may get very hot whilst unthawed material stays frozen. Therefore for balanced heating the thermal effects must be evenly distributed, i.e. there should not be pockets of salty water within a poorly conducting matrix."
from: http://www.lsbu.ac.uk/water/microwave.html
and simpler explanation is at:http://www.colorado.edu/physics/2000/microwaves/water_rotates5.html
2007-01-19 09:00:34 · answer #4 · answered by a simple man 6 · 1⤊ 0⤋
You are experiencing latent heat.
The latent heat of ice is very high - it takes about as much energy to melt ice as it does to heat the water produced to 100C. But you are making the false assumption that it should take very little energy to do this.
This high latent heat is why the seas do not generally freeze in winter, and why maritime areas are warmer than continental ones.
2007-01-19 08:55:29 · answer #5 · answered by Anonymous · 1⤊ 0⤋
heat required to melt the ice (for phase transformation) is much higher than the heat required to raise temperature of water or other similar liquid
2007-01-19 23:48:00 · answer #6 · answered by vikramgoodboy 1 · 1⤊ 0⤋
Perhaps ice cubes dont absorb microwaves?
2007-01-19 11:25:09 · answer #7 · answered by Anonymous · 0⤊ 0⤋