Electromagnetic Waves - Result Question 22

22. The condition under which a microwave oven heats up a food item containing water molecules most efficiently is

[2013]

(a) the frequency of the microwaves has no relation with natural frequency of water molecules.

(b) microwaves are heat waves, so always produce heating.

(c) infra-red waves produce heating in a microwave oven.

(d) the frequency of the microwaves must match the resonant frequency of the water molecules.

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Answer:

Correct Answer: 22. (d)

Solution:

  1. (d) Required condition: Frequency of microwaves $=$ Resonant frequency of water molecules.