A potentiometer wire of length 1.5 m and resistance 15 Ω is connected to a 6 V battery. A cell of emf E balances at 0.3 m. The value of E is:
Correct answer: B. 1.2V
- A. 1V
- B. 1.2V
- C. 1.5V
- D. 2V
Explanation
Potential gradient = V/L = 6/1.5 = 4 V/m. EMF of the cell = gradient × balance length = 4 × 0.3 = 1.2 V.
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About Current Electricity
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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