Question

Assertion (A): Microwave oven heats a food item containing water molecules most efficiently.
Reason (R): Resonant frequency of water molecules matches the frequency of microwaves generated by microwave oven.

• (A) and (R) are true and (R) is the correct explanation of (A)
• (A) and (R) are true but (R) is not the correct explanation of (A)
• (A) is true, but (R) is false
• (A) is false, (R) is true

Hint:

Microwave ovens heat polar molecules like water efficiently because the frequency of microwaves is close to the rotational resonance frequency of water, converting electromagnetic energy into thermal energy effectively.

Answer 1

The Correct Option is A

Step 1: Assertion analysis.
Microwave ovens efficiently heat food, particularly items with water, because water absorbs microwave energy and converts it to heat.

Step 2: Underlying mechanism.
The oscillating electric field of microwaves torques polar water molecules, causing rotational friction and thermal generation.

Step 3: Resonance concept.
Water molecules possess natural rotational frequencies; when microwave frequency approaches resonance, energy uptake maximizes.

Step 4: Reason verification.
The reason correctly states that microwave frequency is close to water's resonant frequency, explaining the efficient heating.

Step 5: Relationship between A and R.
The reason provides the correct physical basis for the assertion.

Step 6: Conclusion.
Both assertion and reason are true, and the reason correctly explains the assertion.