A neon flashlight cell with an emf of 1.5V gives a current of 15A when connected directly to an ammeter of resistance 0.040 Ohms. The internal resistance of the cell is?
Correct answer: B. 0.060 Ohms
- A. 0.00040 Ohms
- B. 0.060 Ohms
- C. 0.10 Ohms
- D. 0.13 Ohms
Explanation
emf= 1.5 VI = 15 AThe resistance of the ammeter in the circuit is = R = 0.04-ohm I = ε / R + r (r is the internal resistance of the cell)15 = 1.5 / r + 0.04r + 0.04 = 1.5 / 15r + 0.04 = 0.1r = 0.1 - 0.04r = 0.06 ohm.
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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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