MadSci Network: Physics

Re: What happens when you heat an object which is on fire in a microwave?

Date: Fri Apr 14 14:35:37 2000
Posted By: Chris Seaman, Staff, Electrical Engineering, Materials Engineering, Alcoa Technical Center
Area of science: Physics
ID: 955033690.Ph

You're hunch about the "electricity" being related to ball lightning and 
plasma is correct.

One way to think about the operation of a microwave oven is that it's an 
"echo chamber" for an electric field.  The field is "tuned" to get water 
molecules jiggling back and forth and heat substances up via molecular 

Plasma is a gaseous form of matter with an equal amount of positive and 
negative species (such as electrons and ions).  Plasmas are conductive, so 
when you lit the toothpicks, the hot gases around the flame were 
allowing local conduction of the electric field within the microwave 
chamber; you were locally "short circuiting" the field.  That's why you saw 
the glowing discharge or arcs around the flame.  You get the same "short 
circuiting" effect when you place a metallic object in the microwave; hence 
the warnings on certain packaging.

I hope your mom didn't catch you.  I'm not sure she'd buy the old "I'm 
experimenting with plasma physics" excuse.

Chris Seaman

Current Queue | Current Queue for Physics | Physics archives

Try the links in the MadSci Library for more information on Physics.

MadSci Home | Information | Search | Random Knowledge Generator | MadSci Archives | Mad Library | MAD Labs | MAD FAQs | Ask a ? | Join Us! | Help Support MadSci

MadSci Network,
© 1995-2000. All rights reserved.