The unit of resistivity is MCQ with Answer and Explanation

Explanation:
ΔL = α L₀ ΔT => α = ΔL/(L₀ ΔT) = 0.0019/(1×100) = 1.9×10⁻⁵ /°C. Typical for brass. Unit is per °C. Always check ΔL/L per °C.

Explanation:
F ∝ m₁m₂. Initial: 1×1 = 1. New masses 2 and 2, product 4, so force = 4F. Distance unchanged. Universal gravitation F = Gm₁m₂/r².

Explanation:
Ohm's law V = IR holds for ohmic conductors (metals) provided temperature and physical conditions constant. Non-ohmic: semiconductors, diodes, electrolytes. Graph V-I is straight line for ohmic. Temperature changes resistance, so condition necessary.