In standard AC household supply in India, the frequency of the alternating current is 50 Hz. How many times per second does the current change its direction? MCQ with Answer and Explanation
In standard AC household supply in India, the frequency of the alternating current is 50 Hz. How many times per second does the current change its direction?
A. 50 times
B. 25 times
C. 0 times
D. 100 times
Answer: Option D
Solution (By JKSSB Mock Tests)
A frequency of 50 Hz means there are 50 complete wave cycles per second. A single complete sinusoidal cycle consists of one positive half-cycle and one negative half-cycle. Therefore, the current reaches zero and reverses its direction exactly twice during each complete cycle. For 50 cycles, the current changes direction 50 * 2 = 100 times per second.
Explanation:
Alpha particles are helium nuclei (2 protons, 2 neutrons), charge +2e, mass 4 u. Beta particles are fast electrons (or positrons). Gamma rays are high-energy photons, no mass, no charge.
Explanation:
Equipotential surface has constant potential V everywhere. Work done W = qΔV; since ΔV = 0 along equipotential, W = 0. This holds for any path on the surface. Electric field is perpendicular to equipotential surfaces, so no work is done moving charge along them. Memory aid: 'Equipotential: ΔV=0 ⇒ W=0; field lines ⊥ equipotentials'. This electrostatics concept is frequently tested in competitive exams. Always link work to potential difference, not absolute potential; path independence is key for conservative fields.
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