A Carnot engine operates between 400 K and 300 K. Its efficiency is: MCQ with Answer and Explanation
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Question #1
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Escape velocity depends on:
Correct Answer: Option A
Explanation:
v_e = √(2GM/R): depends on planet's M and R, independent of projectile mass or launch direction. Memory tip: 'v_e ∝ √(M/R); property of planet, not projectile'. Gravitation concept frequently tested in competitive exams.
v_e = √(2GM/R): depends on planet's M and R, independent of projectile mass or launch direction. Memory tip: 'v_e ∝ √(M/R); property of planet, not projectile'. Gravitation concept frequently tested in competitive exams.
Question #2
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Dispersion occurs because:
Correct Answer: Option C
Explanation:
n varies with λ ⇒ v = c/n varies ⇒ different refraction angles (Snell's law). Frequency constant; wavelength changes in medium. Memory aid: 'Dispersion: n(λ) ⇒ v(λ) ⇒ different bending; violet bends most'. Optics concept frequently tested in competitive exams.
n varies with λ ⇒ v = c/n varies ⇒ different refraction angles (Snell's law). Frequency constant; wavelength changes in medium. Memory aid: 'Dispersion: n(λ) ⇒ v(λ) ⇒ different bending; violet bends most'. Optics concept frequently tested in competitive exams.
Question #3
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During the melting of ice at 0°C, the temperature remains constant because the heat supplied is used to:
Correct Answer: Option C
Explanation:
During phase change (melting), heat energy (latent heat) is used to overcome intermolecular forces, increasing potential energy while kinetic energy (hence temperature) remains constant. Temperature reflects average kinetic energy; since it doesn't change, kinetic energy is unchanged. The energy breaks hydrogen bonds in ice, allowing molecules to move freely in liquid. Memory tip: 'Latent heat changes state, not temperature'. This conceptual question tests understanding of microscopic interpretation of phase changes, frequently examined in competitive tests to assess depth beyond formula recall.
During phase change (melting), heat energy (latent heat) is used to overcome intermolecular forces, increasing potential energy while kinetic energy (hence temperature) remains constant. Temperature reflects average kinetic energy; since it doesn't change, kinetic energy is unchanged. The energy breaks hydrogen bonds in ice, allowing molecules to move freely in liquid. Memory tip: 'Latent heat changes state, not temperature'. This conceptual question tests understanding of microscopic interpretation of phase changes, frequently examined in competitive tests to assess depth beyond formula recall.
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