The force between two charges in vacuum is F. If a medium of dielectric constant 4 is introduced, force becomes MCQ with Answer and Explanation

Explanation:
g' = g (R/(R+h))². If h=R, g' = g (R/2R)² = g/4. Weight = mg' = mg/4, one-fourth. Above surface, g decreases with square of distance from centre.

Explanation:
Ideal gas: no intermolecular forces ⇒ internal energy = kinetic energy ∝ T. U = f/2 nRT. Memory tip: 'Ideal gas: U = U(T) only; real gases have V dependence'. Thermodynamics concept frequently tested in competitive exams.

Explanation:
Speed constant implies magnitude of velocity constant, so kinetic energy (½mv²) is constant. Velocity changes due to direction change. Acceleration (centripetal) is directed towards centre, changes direction. Linear momentum vector changes. So only kinetic energy remains constant.