The condition under which a microwave oven heats up a food item containing water molecules most efficiently is:
Infra-red waves produce heating in a microwave oven.
The frequency of the microwaves must match the resonant frequency of the water molecules.
The frequency of the microwaves has no relation with natural frequency of water molecules.
Microwaves are heat waves, so always produce heating.
When frequency of microwave radiation match the resonant frequency of the water molecule, the rate of energy transfer is maximum and hence heating is most sfficient.
Option 1)
Infra-red waves produce heating in a microwave oven.
This is incorrect option
Option 2)
The frequency of the microwaves must match the resonant frequency of the water molecules.
This is correct option
Option 3)
The frequency of the microwaves has no relation with natural frequency of water molecules.
This is incorrect option
Option 4)
Microwaves are heat waves, so always produce heating.
This is incorrect option