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. Water in a porcelain container is placed in a microwave oven to heat it. The temperature of the water rises, but the container temperature does not rise much. This is because a) porcelain is a bad conductor of heat. b) water is a liquid and can set up convection currents but the container is solid non conductor. c) preferential absorption of microwaves of certain frequencies by water. d) microwaves are more energetic than infrared waves.

. Water in a porcelain container is placed in a microwave oven to heat it. The temperature
of the water rises, but the container temperature does not rise much. This is because
a) porcelain is a bad conductor of heat.
b) water is a liquid and can set up convection currents but the container is solid non
conductor.
c) preferential absorption of microwaves of certain frequencies by water.
d) microwaves are more energetic than infrared waves.

Grade:

1 Answers

Saurabh Koranglekar
askIITians Faculty 10335 Points
3 years ago

Microwave ovens emit waves at the correct wavelength to excite the O-H ( Oxygen —Hydrogen) molecular bond. This bond is found in water, and many other molecules in food, such as sugars, starches and proteins. This excitation of the bond add energy to the molecule, causing it to heat up, and so heats up the food. Glass, porcelain and plastic tend to have few to no OH bonds, so do not absorb these microwaves strongly, and so don’t heat up much.

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