Radioactivity is a phenomenon associated with MCQ with Answer and Explanation

Explanation:
In uniform circular motion, speed is constant but velocity direction changes continuously, requiring centripetal acceleration directed toward the center (a = v²/r). By Newton's second law, a centripetal force must act. Velocity isn't constant (direction changes); acceleration isn't zero; force is required. Memory tip: 'Uniform circular motion: constant speed, changing velocity, center-seeking acceleration'. This conceptual question tests understanding of circular dynamics, crucial for mechanics in competitive exams. Always distinguish speed (scalar) from velocity (vector) in motion analysis.

Explanation:
Microwaves (2.45 GHz) are absorbed by water, fat, sugar molecules, causing them to rotate and generate heat through dielectric heating. Not induction (metal). Not conventional convection.

Explanation:
Volt = J/C. Named after Alessandro Volta. Potential difference drives current. 1 V = 1 J of work per coulomb charge moved.