Specific boiling point ?
Discussion
It's not because jam has a low boiling point. It doesn't - it's slightly higher than water. If it had a low boiling point it wouldn't get as hot.
Microwaves work via dielectric heating. They move polar molecules about and the friction of them rubbing together does the heating. Stuff that has polar molecules that are free to move (like water...or jam) heats up faster than stuff where the molecules can't move as much (like donut dough).
Microwaves work via dielectric heating. They move polar molecules about and the friction of them rubbing together does the heating. Stuff that has polar molecules that are free to move (like water...or jam) heats up faster than stuff where the molecules can't move as much (like donut dough).
hairykrishna said:
It's not because jam has a low boiling point. It doesn't - it's slightly higher than water. If it had a low boiling point it wouldn't get as hot.
Microwaves work via dielectric heating. They move polar molecules about and the friction of them rubbing together does the heating. Stuff that has polar molecules that are free to move (like water...or jam) heats up faster than stuff where the molecules can't move as much (like donut dough).
you learn something new everyday ," everyday's a new day"Microwaves work via dielectric heating. They move polar molecules about and the friction of them rubbing together does the heating. Stuff that has polar molecules that are free to move (like water...or jam) heats up faster than stuff where the molecules can't move as much (like donut dough).
Road Hog said:
why has jam got such a low boiling point ?
just put nice jammy doughnut in microwave for a few seconds ,and when it came out the jam was hot enough to take your skin off.....
Well... boiling in itself is no sign of something being hot... ether boils at about 35 degrees or so and surely you wouldn't burn yourselves with boiling ether.just put nice jammy doughnut in microwave for a few seconds ,and when it came out the jam was hot enough to take your skin off.....
Thus, your question is not correct. Jam does not have a low boiling point, and sugars etc. would increase it rather than lower it.
The question is why it apparently heats up so quickly. My hunch would be that the actual amount heated in your doughnut isn't very large and probably somewhat thinly spread, so not so much microwave energy is needed to heat it significantly. Cue you burning yourself.
Maarten
Edited to say: Damned, beaten to it!
Another edit: probably you also have to take into account that the heat generated in the jam cannot escape so well because it is encased in dough so it retains the heat better - cue you burning yourself even more.
Edited by mmertens on Tuesday 24th March 10:55
Edited by mmertens on Tuesday 24th March 10:59
Yesterday I'm fairly sure I made a discovery that could solve all of mans energy needs.
Simply heating a pitta bread in a toaster for a minute or so creates an air temperature inside that is hotter than the centre of the Sun.
The resulting jet of air/plasma from said pitta bread can be used like a laser cutter.
In fact, I think the Death Star was just a massive toaster with pitta breads in it.
Simply heating a pitta bread in a toaster for a minute or so creates an air temperature inside that is hotter than the centre of the Sun.
The resulting jet of air/plasma from said pitta bread can be used like a laser cutter.
In fact, I think the Death Star was just a massive toaster with pitta breads in it.
DrTre said:
Yesterday I'm fairly sure I made a discovery that could solve all of mans energy needs.
Simply heating a pitta bread in a toaster for a minute or so creates an air temperature inside that is hotter than the centre of the Sun.
The resulting jet of air/plasma from said pitta bread can be used like a laser cutter.
In fact, I think the Death Star was just a massive toaster with pitta breads in it.
...and a cow is a stealth vegetable!Simply heating a pitta bread in a toaster for a minute or so creates an air temperature inside that is hotter than the centre of the Sun.
The resulting jet of air/plasma from said pitta bread can be used like a laser cutter.
In fact, I think the Death Star was just a massive toaster with pitta breads in it.
See!!!
Road Hog said:
back on thread ,
if a liquid has a very low boiling point ,would ,could you be burnt/scolded.?from it
Yes - liquid nitrogen boils at a low temp and you can be burned by it.if a liquid has a very low boiling point ,would ,could you be burnt/scolded.?from it
As for the superheating thing, yep - thats why the tray in your micro spins, take it out and microwave a cup of water, watch what happens when you move the cup (really do not do this)
If you are a sad b
d you can use your microwave to measure the speed of light. Remove turntable, put big bar of chocolate in there, wait till it starts to melt. The distance between the melted spots on the choccy is the wavelength of the microwaves. Get the frequency from the manufacturer or from the side of the micro and then multiply the wavelength by the frequency to get the speed of light 
Road Hog said:
back on thread ,
if a liquid has a very low boiling point ,would ,could you be burnt/scolded.?from it
Not easily. A liquid that's at it's boiling point won't raise in temperature if more heat energy is supplied - it will go through a phase transition instead (i.e boil!). So, unless it's in some kind of sealed container, the liquid won't ever be hotter than its boiling point.if a liquid has a very low boiling point ,would ,could you be burnt/scolded.?from it
It's actually slightly more complicated than that because a liquid can be raised above it's boiling point without boiling - 'superheating'. This is because surface tension stops bubbles forming. It only happens in very clean containers where there aren't any imperfections to help the initial formation of the bubbles. I only mention it because it happens occasionally in microwaves! You can do it deliberately (extremely dangerous experiment warning) if you coat the inside of a mug or glass with cooking oil then fill with water and heat in the microwave. The water won't boil (not for ages anyway) until a nucleation site is introduced - like a spoon or something. Then majority of the water will then explode into very hot steam. Moving the mug or glass sometimes does it too...
Parsnip said:
Yes - liquid nitrogen boils at a low temp and you can be burned by it.
Good point. Very cold stuff can burn you too although it is actually pretty tricky to burn yourself with LN2. It tends to boil off before coming in contact with your skin. Don't touch metal stuff that's been sat in it though! I think the OP was thinking more of stuff that boils at 30 degrees rather than -196 though...
DrTre said:
Yesterday I'm fairly sure I made a discovery that could solve all of mans energy needs.
Simply heating a pitta bread in a toaster for a minute or so creates an air temperature inside that is hotter than the centre of the Sun.
The resulting jet of air/plasma from said pitta bread can be used like a laser cutter.
In fact, I think the Death Star was just a massive toaster with pitta breads in it.
I did work experience in a chippy and can confirm that pitta breads are the only substance known to man that are hotter than hot apple pie, which in itself is hotter than the sun.Simply heating a pitta bread in a toaster for a minute or so creates an air temperature inside that is hotter than the centre of the Sun.
The resulting jet of air/plasma from said pitta bread can be used like a laser cutter.
In fact, I think the Death Star was just a massive toaster with pitta breads in it.
Gassing Station | The Pie & Piston Archive | Top of Page | What's New | My Stuff