Resistance R of a wire is R = ρ (l / A) = ρ (l / πr²). Given l₁:l₂:l₃ = 2:3:4 and r₁:r₂:r₃ = 3:4:5, solving for I, the ratio is 54:64:75. Answer: (b) 54:64:75.
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For n identical resistors of resistance R: Series combination: S = nR Parallel combination: P = R/n Given 5 = nP, substituting P = R/n: 5 = n (R/n) ⇒ 5 = R, so n = 4. Answer: (d) 4.
Total resistance Rₜ = 21Ω + 4Ω = 25Ω. Using V = IR = 0.2 × 25 = 5V. Power P = VI = 5 × 0.2 = 1W = 1 J/s. Answer: (d) 1 J/s.
Ans. The terminal voltage equation is V = ɛ – Ir, comparing with y = mx + c, the slope is -r and the intercept is ɛ. Thus, the correct answer is (a) -r and ɛ.
Let each cell have emf E and internal resistance r. For aiding: (12E + 2E) / R = 3A → 14E/R = 3. For opposing: (12E – 2E) / R = 2A → 10E/R = 2. Solving, x = 2 ...