Two batteries (E₁ = 12 V, r₁ = 1 Ω; E₂ = 6 V, r₂ = 2 Ω) are connected in series with a 9 Ω resistor, with E₂ opposing E₁. The potential difference across the 9 Ω resistor is:
Correct answer: A. 4.5 V
- A. 4.5 V
- B. 7V
- C. 8V
- D. 9V
Explanation
Net emf = 12 - 6 = 6 V. Total resistance = 1 + 2 + 9 = 12 Ω. Current I = 6/12 = 0.5 A. Voltage across 9 Ω = I × R = 0.5 × 9 = 4.5 V. Thus, option A is correct.
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Steady current relates charge flow to potential difference, resistance and resistivity, including how temperature changes a conductor's resistance. Sources with internal resistance have terminal voltage below their emf when delivering current, and maximum power output occurs under a specific load condition rather than at zero resistance.
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