A bimetallic strip is used in MCQ with Answer and Explanation
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Question #1
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A microwave oven heats food primarily by exciting which specific molecules in the food?
Correct Answer: Option A
Explanation:
Microwave ovens use electromagnetic radiation in the microwave frequency range (usually around 2.45 GHz). Water molecules have a permanent electric dipole moment. The oscillating electric field of the microwaves rapidly forces the water molecules to flip back and forth to align with the field, generating thermal energy via friction and effectively heating the food from within.
Microwave ovens use electromagnetic radiation in the microwave frequency range (usually around 2.45 GHz). Water molecules have a permanent electric dipole moment. The oscillating electric field of the microwaves rapidly forces the water molecules to flip back and forth to align with the field, generating thermal energy via friction and effectively heating the food from within.
Question #2
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The principle of a lightning conductor is
Question #3
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The universal law of gravitation states that the force between two masses is directly proportional to:
Correct Answer: Option A
Explanation:
Newton's law of gravitation: F = G·m₁m₂/r². Thus force is directly proportional to the product of the masses (m₁m₂) and inversely proportional to square of distance (r²). Option D incorrectly states 'directly proportional to square of distance' – it's inverse square. This fundamental law governs celestial mechanics. Memory tip: 'F ∝ m₁m₂ and F ∝ 1/r²'. Competitive exams often test precise wording of physical laws; distractors may reverse proportionality or misstate dependencies. Always recall the exact mathematical form.
Newton's law of gravitation: F = G·m₁m₂/r². Thus force is directly proportional to the product of the masses (m₁m₂) and inversely proportional to square of distance (r²). Option D incorrectly states 'directly proportional to square of distance' – it's inverse square. This fundamental law governs celestial mechanics. Memory tip: 'F ∝ m₁m₂ and F ∝ 1/r²'. Competitive exams often test precise wording of physical laws; distractors may reverse proportionality or misstate dependencies. Always recall the exact mathematical form.
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