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

Explanation:
SHM definition: acceleration a ∝ -x (displacement), i.e., a = -ω²x. This restoring acceleration causes oscillatory motion. Constant acceleration implies uniformly accelerated motion (not oscillatory). Constant velocity implies no acceleration. Memory tip: 'SHM: a = -ω²x; force F = -kx (Hooke's law)'. This conceptual question tests fundamental SHM characteristics, frequently examined in competitive exams. Always link to examples: mass-spring system, simple pendulum (small angles), LC circuits.

Explanation:
Kepler's 3rd law: T² ∝ R³ => T' = T (4)^(3/2) = T×8 = 8T.

Explanation:
Inside a long solenoid, magnetic field is uniform (constant magnitude and direction), parallel to the axis, given by B = μ₀nI, where n is turns per unit length. Outside, field is nearly zero. This uniformity makes solenoids useful for creating controlled magnetic fields. Memory tip: 'Solenoid: uniform B inside like bar magnet'. This conceptual question tests knowledge of magnetic field configurations, crucial for electromagnetism in competitive exams. Always distinguish solenoid field (uniform inside) from straight wire field (circular, non-uniform).