The speed of sound in air at 20°C is approximately MCQ with Answer and Explanation

Explanation:
Joule's law states that heat produced H = I²Rt, where I is current, R resistance, t time. This quantifies electrical energy converted to thermal energy in resistors. Ohm's law relates V, I, R; Faraday's and Lenz's laws concern electromagnetic induction. Memory aid: 'Joule heating ∝ I²R'. This definition-based question tests knowledge of fundamental laws in electricity, commonly examined in competitive exams. Applications include electric heaters, fuses, and incandescent bulbs. Always distinguish Joule's law (heating) from power formulas (P=VI=I²R=V²/R).

Explanation:
Proton mass ≈ 1.67 × 10⁻²⁷ kg, electron ≈ 9.11 × 10⁻³¹ kg, ratio ≈ 1836. Neutron slightly heavier. Atomic mass concentrated in nucleus.

Explanation:
Angular momentum (L = mvr) has dimensions [ML²T⁻¹]. Planck's constant (h = E/ν) also has dimensions [ML²T⁻¹]. They share the same dimensional formula. Force is [MLT⁻²], Power is [ML²T⁻³], Momentum is [MLT⁻¹], and Strain is a dimensionless quantity [M⁰L⁰T⁰]. This is a frequent exam question.