Solar cells (photovoltaic cells) convert light energy (photons) directly into electrical energy via the photovoltaic effect: photons excite electrons in semiconductor material, creating electron-hole pairs that generate voltage. This is distinct from solar thermal (light to heat to electricity) or batteries (chemical to electrical). Memory aid: 'Photo = light; voltaic = electricity'. This renewable energy application question tests knowledge of energy conversion principles, common in competitive exams. Always distinguish photovoltaic (direct light-electricity) from other solar technologies.
Explanation:
Using the second equation of motion for free fall: h = ut + ½gt². Since it is dropped, initial velocity (u) = 0. Time (t) = 4s, g = 10 m/s². The height h = 0 + ½(10)(4)² = 5 × 16 = 80 meters.
Explanation:
V_s/V_p = N_s/N_p ⇒ V_s = 100×(5/1) = 500V. Step-up transformer increases voltage. Memory aid: 'Turns ratio = voltage ratio; current ratio inverse'. Direct transformer formula application frequently tested in competitive exams with ratio calculations.
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