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The condition under which a microwave o...

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

A

1) the frequency of the microwave must match the resonant frequency of the water molecules

B

2) the frequency of the microwave has no relation with natural frequency of water molecules

C

3) microwave are heat waves, so always produce heating

D

4) infra-red waves produce heating in a micorwave oven

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The correct Answer is:
To determine the condition under which a microwave oven heats up a food item containing water molecules most efficiently, we can follow these steps: ### Step-by-Step Solution: 1. **Understand the Mechanism of Heating in Microwave Ovens**: - Microwaves are a form of electromagnetic radiation that specifically interact with polar molecules, such as water. When microwaves pass through food, they cause water molecules to vibrate. 2. **Identify the Resonant Frequency**: - Each molecule has a natural resonant frequency at which it vibrates most efficiently. For water molecules, this frequency corresponds to the frequency of the microwaves used in the oven. 3. **Match Frequencies for Efficient Heating**: - The efficiency of heating occurs when the frequency of the microwaves matches the resonant frequency of the water molecules. This resonance allows for maximum energy transfer from the microwaves to the water molecules, increasing their kinetic energy and thus heating the food. 4. **Evaluate the Options**: - Option 1 states that the frequency of the microwave must match the resonant frequency of the water molecules. This is the correct condition for efficient heating. - Option 2 suggests there is no relation between the microwave frequency and the natural frequency of water molecules, which is incorrect. - Option 3 claims that microwaves are heat waves and always produce heat, which is misleading as the efficiency depends on frequency matching. - Option 4 mentions infrared waves, which are not the primary heating mechanism in microwave ovens. 5. **Conclusion**: - The most efficient heating of food containing water occurs when the frequency of the microwave matches the resonant frequency of the water molecules. Thus, the correct answer is option 1. ### Final Answer: The condition under which a microwave oven heats up a food item containing water molecules most efficiently is: **The frequency of the microwave must match the resonant frequency of the water molecules.** ---
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