The frequency of infrasound is MCQ with Answer and Explanation

Explanation:
Coefficient of performance (COP) for refrigerator: COP = Q₂ / W, where Q₂ is heat extracted from cold reservoir, W is work input. By energy conservation, Q₁ = Q₂ + W (heat rejected to hot reservoir). COP > 1 typically. Option A is inverse; C and D relate to heat engine efficiency. Memory aid: 'Refrigerator COP = desired output (cooling) / work input'. This thermodynamics definition is frequently tested in competitive exams. Always distinguish refrigerator COP (cooling effect per work) from heat engine efficiency (work output per heat input).

Explanation:
Generator works on electromagnetic induction.

Explanation:
Moderator (water, graphite) slows fast neutrons to thermal energies for efficient fission in U-235. Control rods absorb neutrons to regulate reaction. Memory tip: 'Moderator = neutron slower; Control rods = neutron absorber'. Reactor component function frequently tested in competitive nuclear physics questions.