A transformer has 400 primary turns and 100 secondary turns. If primary voltage is 220 V, secondary voltage is MCQ with Answer and Explanation

Explanation:
F = Gm₁m₂/r² ⇒ G = Fr²/(m₁m₂) = [MLT⁻²][L²]/[M²] = [M⁻¹L³T⁻²]. Memory aid: 'G dimensions: [M⁻¹L³T⁻²]; small value reflects weak gravity'. Dimensional analysis frequently tested in competitive exams.

Explanation:
Weight = mg = 10×10 = 100 N. In free fall, only force is gravity (air resistance neglected). Net force = weight, so F = 100 N, causing acceleration g.

Explanation:
The thermal efficiency (η) of a reversible Carnot engine depends exclusively on the absolute temperatures of the hot source (T1) and the cold sink (T2). The formula is η = 1 - (T2/T1), or (T1 - T2) / T1. Temperatures must be in Kelvin. It shows no engine can be 100% efficient unless the sink is at absolute zero.