Question

To heat the food containing water, the frequency of the microwaves used in microwave oven is:

• A. independent of the resonant frequency of water molecules.
• B. equal to the resonant frequency of water molecules.
• C. 100 times the resonant frequency of water molecules.
• D. \( \frac{1}{100} \) times the resonant frequency of water molecules.

Hint:

For effective microwave heating, the frequency of microwaves must match the resonant frequency of water molecules to maximize energy absorption.

Answer 1

The Correct Option is B

Step 1: Understanding Microwave Heating:
In a microwave oven, the microwaves used to heat food work by causing the water molecules to vibrate. This vibration creates heat through friction, which raises the temperature of the food. The key principle is that the microwave frequency must match the natural resonant frequency of water molecules for efficient heating. Step 2: Resonance:
When a system (like water molecules) is exposed to a frequency that matches its natural resonant frequency, the system absorbs energy most efficiently. In the case of microwave ovens, the frequency of the microwaves is designed to match the resonant frequency of water molecules, which causes them to oscillate at a high rate and generate heat. Step 3: Why the Frequency Must Match:
If the microwave frequency is not equal to the resonant frequency of the water molecules, the energy transfer will not be as effective, and the food will not heat up efficiently. This is why the frequency of the microwaves in a microwave oven is specifically chosen to match the resonant frequency of water molecules. Step 4: Conclusion:
Therefore, the correct answer is (2) equal to the resonant frequency of water molecules, as this ensures efficient energy absorption and effective heating.