The essential difference between AC and DC is MCQ with Answer and Explanation

Explanation:
J.J. Thomson measured e/m using cathode ray deflection (1897). Millikan later measured e (oil drop). Memory aid: 'Thomson = e/m; Millikan = e'. Experimental physics history frequently tested in competitive exams.

Explanation:
Convex mirror diverges rays, gives erect, diminished, virtual image with wider field. Concave would magnify but narrow field. Plane gives normal view. Safety advantage.

Explanation:
Acceleration a = dv/dt = d(3t² + 2t)/dt = 6t + 2. At t = 2 s: a = 6(2) + 2 = 14 m/s². Differentiation of velocity gives instantaneous acceleration. Memory tip: a = dv/dt; for polynomial v(t), differentiate term by term. Tests calculus application in kinematics, common in advanced competitive exam questions.