The work done in moving a charge of 2 C between two points with potential difference of 12 V is:
A. 6 J
B. 14 J
C. 0.167 J
D. 24 J
Answer: Option D
Solution (By JKSSB Mock Tests)
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:
R ∝ L/A. New L'=2L, A'=A/2 => R' = ρ(2L)/(A/2) = 4ρL/A = 4R. Alternatively, volume constant? Not given, here both changed independently. So 4R.
If a stone is dropped from a balloon rising upwards with a velocity of 10 m/s at a height of 75 m, what is the initial velocity of the stone relative to the ground?
Explanation:
Due to the inertia of motion, when an object is dropped from a moving vehicle (or balloon), it inherits the instantaneous velocity of that vehicle. Since the balloon was moving upwards at 10 m/s, the stone's initial velocity relative to the ground is 10 m/s upwards. It will rise slightly before falling.
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