Pressure at depth h in fluid: P = P₀ + ρgh. If depth doubles, pressure increase is: MCQ with Answer and Explanation

Explanation:
An AC generator uses continuous 'slip rings' which allow the output polarity to reverse every half-rotation of the coil, generating alternating current. To produce direct current (DC), the slip rings must be replaced by a 'split-ring commutator'. This commutator reverses the connections to the external circuit at the exact moment the coil's current reverses, ensuring current flows in only one direction outside.

Explanation:
The velocity of sound in a medium is determined by the formula v = √(E/ρ), where E is the modulus of elasticity and ρ is the density. Although solids are denser, their modulus of elasticity (bulk modulus) is tremendously higher than that of gases, overwhelmingly compensating for the density. Hence, sound travels fastest in solids.

Explanation:
For parallel combination: 1/R_eq = 1/R₁ + 1/R₂ + 1/R₃ = 1/2 + 1/3 + 1/6 = (3+2+1)/6 = 6/6 = 1. Thus R_eq = 1Ω. Note: Equivalent resistance in parallel is always less than the smallest individual resistance (here 2Ω). Memory tip: 'Parallel: reciprocal sum; result < min(R)'. This standard calculation tests parallel resistance formula application, frequently appearing in competitive exams. Always simplify fractions carefully; common denominator method avoids errors. Verify: 1Ω < 2Ω, consistent with parallel behavior.