Microwave Flashcards
What is the history of the microwave? How does it work ?
Magnetron generates microwave radio signals In WWII - used in tracking the enemy Post War - used for heating food
What are microwaves ? (1/3)
Nonionizing waves of energy that create thermal changes
What are microwaves ? (2/3)
Do not cause dangerous chemical changes (as do ionizing rays)
What are microwaves ? (3/3)
Absorbed, transferred or reflected depending on the composition of the material with which it is in contact
How do microwave ovens work ?
Transfer of heat via electromagnetic radiation Waves Magnetron Dielectric heating
What is a magnetron ?
Vacuum electron tube that converts household electricity into microwaves. -emits microwaves set in motion by a fan -turntable helps cook evenly - different power outputs
What are the two different power outputs of a magnetron?
Général: 500-750 watts Commercial: 1000-1300
How do waves function in microwaves ?
Emitted from an opening in the metal case Reflected off the sides and penetrate food in the process
How does dielectric heating work in microwaves ?
-High frequency and alternating electromagnetic field heats a dielectric material -polarity reversals
What are the two major interactions in dielectric heating ?
1) dipolar rotation molecules (with positive and negative pokes) 2) ionic conduction (electrically charged ions) BOTH types generate heat by friction and transfer to other molecules by conduction
Recommended containers for microwaving ?
- must be able to TRANSFER microwaves (not absorb or reflect) -round -shallow No recycled paper or brown bags No metals dishes
Why round containers ?
Fan is circular - even heating. Microwaves enter only 1 inch into food.
Why no metals dishes ?
Arching Accumulation of electrons Not « terrible » why?
What are some guidelines for using metal ?
- reasonably large -Kept away from walls - metal/foil is grounded along the bottom of the microwave
Why should you stir food in microwave?
Since food is only heated writhing 1in, stir to endure thorough cooking
Can you microwave spoons or forks?
Spoons are a better choice - don’t build up charge, rather spread charge around the spoon = less sparking
How should you arrange containers in a microwave ?
-foods cook from the OUTSIDE ! Position heavier / denser portions on the outside Whenever heating multiple items - the center should be left empty