The phenomenon of persistence of sound due to multiple reflections is called MCQ with Answer and Explanation

Explanation:
d = (v×t)/2 = (340×0.5)/2 = 170/2 = 85 m. Minimum distance for echo perception is about 17 m. Remember divide by 2 for one-way distance.

Explanation:
Neglecting air resistance, total mechanical energy conserved.

Explanation:
Diamagnetic materials have small negative susceptibility (χ ≈ -10⁻⁵), meaning they weakly repel magnetic fields. Paramagnetic: small positive χ; ferromagnetic: large positive χ. This classification is based on response to external magnetic fields. Memory aid: 'Diamagnetic: repelled by magnets; χ < 0'. This conceptual question tests magnetism fundamentals, crucial for competitive exams. Always link susceptibility sign to material behavior: negative χ ⇒ diamagnetic (weak repulsion), positive ⇒ paramagnetic/ferromagnetic (attraction).