The condition under which a microwave oven heats up a food item containing water molecules most efficiently is Option 1) The frequency of the microwaves has no relation with natural frequency of water molecules. Option 2) Microwaves are heat waves, so always produce heating Option 3) Infra-red waves produce heating in a microwave oven. Option 4) The frequency of the microwaves must match the resonant frequency of the water molecules

P Plabita

As we learnt in

Micro Wave -

Frequency Range $10^{9}$ Hz to $3 \times 10^{11}$ Hz

- wherein

Wavelength Range 1 mm to 0.3 mm

Rate of energy transfer is maximum at resonance, hence, heating of water molecule is by microwave is most efficient when frequency of the microwave match the resonant freqeuncy of the water molecule

Option 1)

The frequency of the microwaves has no relation with natural frequency of water molecules.

Incorrect

Option 2)

Microwaves are heat waves, so always produce heating

Incorrect

Option 3)

Infra-red waves produce heating in a microwave oven.

Incorrect

Option 4)

The frequency of the microwaves must match the resonant frequency of the water molecules

Correct

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