Sound requires material medium for mechanical wave propagation. Vacuum lacks particles to transmit vibrations. Light (EM wave) travels through vacuum. Memory tip: 'Sound = mechanical wave ⇒ needs medium; light = EM wave ⇒ no medium needed'. Fundamental wave property frequently tested in competitive exams to assess medium-dependence understanding.
Explanation:
Work done W = charge (Q) × potential difference (V). Thus W = 2 C × 12 V = 24 J. This follows from definition of voltage: 1 volt = 1 joule per coulomb. The work done equals the change in electrical potential energy. This fundamental relationship is crucial in electricity. Memory tip: W = QV is analogous to mechanical work = force × distance. Such direct formula applications are common in competitive exams to test basic concept retention. Always verify units: coulomb × volt = joule, confirming dimensional consistency.
Explanation:
At 0°C, speed ~ 331 m/s. At room temperature (20°C) ~ 343 m/s, often taken as 340. Increases with temperature v ∝ √T. For many problems 340 is used, but at 0°C it's 331. So option A.
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