• We’re currently investigating an issue related to the forum theme and styling that is impacting page layout and visual formatting. The problem has been identified, and we are actively working on a resolution. There is no impact to user data or functionality, this is strictly a front-end display issue. We’ll post an update once the fix has been deployed. Thanks for your patience while we get this sorted.

About microwaves: the middle heats up slower, why?

Turkish

Turkish

Lifer
As the title suggests, why is it that the middle of a pizza slice is the coldest after heating for a certain time? I thought microwaves heated every single part on the food equally? or am i totally wrong? thanks.
 
from "cooking for dummies"
A major misconception is that microwaves cook from the inside out. they do not. microwaves penetrate primarily the surface and no farther than 2 inches into the food. the heat spreads by conuction to the rest of the food
 
all a microwave does in essence is speed up the particles. Since the particles are less dense on the outside of an object they move faster first thus allowing the outter edges to get warmer first
 
all a microwave does in essence is speed up the particles. Since the particles are less dense on the outside of an object they move faster first thus allowing the outter edges to get warmer first
 
my panasonic microwave has a big sticket on it that says inverter microwave and that it cooks "evenly and fully". for like the first 9 months it has cooked things evenly but recently the center of something i heat comes out cold while the outer edges are hot, guess it inverted the inverter
 
Originally posted by: AEB
all a microwave does in essence is speed up the particles. Since the particles are less dense on the outside of an object they move faster first thus allowing the outter edges to get warmer first
Click to expand...

This is pretty much incorrect.


Microwaves are tuned to the bond length of water. A molecular bond can be seen as a small spring, the microwaves give this spring a push which causes the water molecule to vibrate. When the vibrating water molecule collides with a neighboring molecule it transfers this vibrational energy to its neighbor in the from of a extra little kick, this speeds up both the neighbor and the original molecule. Temperature is a measure of molecular motion, so the water inside the microwave get hotter. This tends to heat up anything that contains water.

The microwave penetrate inside the object heating inside as well as outside, but there is a limit. Depending on the water content and density of the object being heated the microwaves may all be adsorbed before reaching the center. In this case the center will have to heat via conduction just as if it were being heated in a standard oven.
 
Also, because the outside heats up first and very quickly, the water that is heated vaporizes readily and never gets a chance to heat up the inside of the food, leaving you with a hot, dry outside and a cold, wet inside. This is why you should never put sealed containers in microwaves, as the pressure will build up quickly, causing an explosion. However, keeping a closed, but slightly vented container is the best way to get good heating, as it keeps most of the hot steam close to the food.
 
This makes me wonder why my ceramic plates come out of the microwave too hot to hold, while my frozen veggies are still chilly.

How do my plates get so hot if there's no water in them??
 
maybe ceramics tend to have bond energies similar to water and ice tends to have different bond energies?

are you sure it's the whole plate that's hot and not just the part right next to the outside of the food? The veggies would still be frozen, as the inside wouldn't have been heated.
 
Well it's not the food heating up the plate, because

a- the entire plate is hot, not just the part next to the food
b- the plate is SCALDING hot while the veggies are still chilly.
 
Try a different plate (meaning not from same set). Had same thing and think it is because moisture content of different manufacturers' plates may vary. Assuming glaze seals in moisture so that repeated microwaving using same plate does not "dry plate out".

Also, pizza slice is just as dense at edges as at center, as mentioned before, limit to how far waves penetrate.

 
Uhh well any ceramics are about as dry as any substance can be; clay is heated to hundreds of degrees for hours expressly to remove all moisture.
 
Only old ceramic plates do that like the ones from the 50s. I got some plates from my parents that were bought in the 80s and they don't heat up like crazy. However, some of the plates that were given to me from my grandma (old ones) heat up just insanely hot. I think it's just because they're old.

There is also a type of plastic from a long time ago (like the 50s) that sucks ass in microwaves. A plastic tupperwear bowl comes out wtih hot food, warm bowl. One of the plastic bowls from the 50s (not bendable at all) comes out extremely hot with cold food inside.
 
Some ceramic glazes have metalic components, the result of this will be exactly what you describe. With the addional bonus of early death of your microwave. This last is not a certianty, but definitly a possiblity.
 
Originally posted by: grant2
This makes me wonder why my ceramic plates come out of the microwave too hot to hold, while my frozen veggies are still chilly.

How do my plates get so hot if there's no water in them??
Click to expand...

try using the "defrost" setting on your microwave next time. Ice has a different resonace frequency to water so it is not affected by ordinary microwaves.
 
Originally posted by: grant2
Uhh well any ceramics are about as dry as any substance can be; clay is heated to hundreds of degrees for hours expressly to remove all moisture.
Click to expand...
If you read what I said, you'd realize that the presence of water is irrelevant.
 
Originally posted by: Shalmanese

try using the "defrost" setting on your microwave next time. Ice has a different resonace frequency to water so it is not affected by ordinary microwaves.
Click to expand...
Does that actually adjust the frequency with your average $50 microwave? I was under the impression that it just lowered the intensity to allow time for the heat to diffuse inside the food and melt all the ice.
 
Originally posted by: rjain
Originally posted by: grant2
Uhh well any ceramics are about as dry as any substance can be; clay is heated to hundreds of degrees for hours expressly to remove all moisture.
Click to expand...
If you read what I said, you'd realize that the presence of water is irrelevant.
Click to expand...

What you said (asked), "maybe ceramics tend to have bond energies similar to water and ice tends to have different bond energies?" suggested you were making a guess.

There's no reason I should take your guesses as fact without collaboration. And that reply wasn't directed to you anywas 🙂
 
It's the glazes in the ceramics that heat up. The ceramics themselves heat up only to the extent that conduction warms them.

Interesting to see a few political types here on this board. Yeah, you. You know who you are!
 
Originally posted by: grant2

What you said (asked), "maybe ceramics tend to have bond energies similar to water and ice tends to have different bond energies?" suggested you were making a guess.

There's no reason I should take your guesses as fact without collaboration. And that reply wasn't directed to you anywas 🙂
Click to expand...
And I indicated that it's not about water or no water... And it's not, that is a fact.
 
Originally posted by: Whitling

Interesting to see a few political types here on this board. Yeah, you. You know who you are!
Click to expand...
You've got it backwards, I'm a scientist by nature. 🙂
 
Originally posted by: rjain
Originally posted by: Shalmanese

try using the "defrost" setting on your microwave next time. Ice has a different resonace frequency to water so it is not affected by ordinary microwaves.
Click to expand...
Does that actually adjust the frequency with your average $50 microwave? I was under the impression that it just lowered the intensity to allow time for the heat to diffuse inside the food and melt all the ice.
Click to expand...

I dunno, stick an ice cube into your $50 microwave and set it on both defrost and normal. See if it makes a difference. I am without microwave atm so I cannot test this. One thing I have found, however, is that defrost only seems to work if you put the object in the microwave without a dish in the way. I always used to put stuff in with a dish so the water wouldnt drip onto the microwave and it always cooked it. No dish and it works great.
 
Oh, and a word of warning, since the normal microwave isn't absorbed by the ice, it might damage your microwave if you dont also put a small bowl of water to absorb the stray rays.
 
I just put a dry ice cube, along with a cup of water, (well actually spiced wine!) after 1 minute, while the wine was nicely warmed the ice cube remained dry. after 2 min the wine is quite hot and the ice cube is starting to get wet. I may well be that the presence of the water vapor created by the hot wine in the microwave.

I am convinced, the molecular structure of ice, which is obviously different from water, is sufficiently different from water as to be mimimally effected by microwaves.

I did not try defrost level, this was done on an 1100W (not $50) microwave.

Could it be that higher power levels any microwave interaction simply sublimates the water, while lower power may not have sufficient power to do this, thus a surface layer of water can develope which will then speed the melting of the ice via convection.

Just guesses, go ahead if you have a better SWAG* factor let me hear your explainations.



*SWAG = Scientific Wild A$$ Guess
 
You must log in or register to reply here.

TRENDING THREADS

Back
Top