The device used to convert solar energy into electrical energy is
A. Wind turbine
B. Solar heater
C. Battery
D. Solar cell
Answer: Option D
Solution (By JKExamLibrary)
Photovoltaic cell (solar cell) directly converts sunlight to electricity. Solar heater uses sun to heat water, not electricity. Wind turbine converts wind energy. Battery stores chemical energy.
Explanation:
Kinetic energy KE = p²/(2m), where p is momentum. Thus p = √(2m·KE). If KE becomes 4 times, p_new = √(2m·4KE) = 2√(2m·KE) = 2p_initial. Hence momentum doubles. This relationship shows momentum scales with square root of kinetic energy for constant mass. Memory tip: p ∝ √KE when mass constant. This conceptual link between momentum and kinetic energy is frequently tested in competitive exams to assess depth of understanding beyond rote formula memorization. Always derive relationships when direct formulas aren't recalled.
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