The force between two charges in vacuum is F. If a medium of dielectric constant 5 is introduced, force becomes MCQ with Answer and Explanation

Explanation:
Conservative forces (gravity, spring): work path-independent ⇒ ∮F·dr = 0 over closed loop. Enables potential energy definition. Memory aid: 'Conservative: ∮F·dr = 0; enables energy conservation'. Mechanics foundation frequently tested in competitive exams.

Explanation:
In uniform circular motion, speed remains constant but direction changes, so velocity (vector) changes. There is centripetal acceleration towards centre, so acceleration is not zero. Kinetic energy = ½mv², depends on speed, so remains constant. Thus, only speed is constant.

Explanation:
Diffraction (bending around obstacles) is wave phenomenon explained by Huygens' principle. Particle model predicts straight-line propagation. Memory aid: 'Diffraction/interference ⇒ wave nature; photoelectric ⇒ particle nature'. Wave-particle duality frequently tested in competitive exams.