Read the information given below.
The basic principle of a microwave oven is to generate microwave radiation of appropriate frequency in the working space of the oven where we keep food. This way energy is not wasted in heating up the vessel. In the conventional heating method, the vessel on the burner gets heated first and then the food inside gets heated because of transfer of energy from the vessel. In the microwave oven, on the other hand, energy is directly delivered to water molecules which is shared by the entire food.
The basic principle of a microwave oven is
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → Resonant frequency of water molecule
The microwaves in the oven are chosen with a frequency that matches the resonant frequency of water molecules. The water molecules absorb this energy efficiently, their kinetic energy increases and the temperature of the food containing water rises.
NCERT (2026-27):
Microwaves – “… Microwave ovens are an interesting domestic application of these waves. In such ovens, the frequency of the microwaves is selected to match the resonant frequency of water molecules so that energy from the waves is transferred efficiently to the kinetic energy of the molecules. This raises the temperature of any food containing water.”