A cell of internal resistance 2.0Ω and electromotive force (e.m.f) 1.5V is connected to a resistor of resistance 3.0Ω. What is the potential difference across the 3.0Ω resistor?
Correct answer: C. 0.9V
- A. 5V
- B. 1.2V
- C. 0.9V
- D. 0.6V
Explanation
Rtotal = Internal resistance of the cell + Resistance of the external resistorRtotal = 2.0Ω + 3.0ΩRtotal = 5.0ΩCalculate the current (I) flowing through the circuit using Ohm's law:I = (e.m.f) / (Rtotal )I = 1.5V / 5.0ΩI = 0.3A (amperes)Finally, calculate the potential difference (V) across the 3.0Ω resistor using Ohm's law:V = I * R (where I is the current and R is the resistance of the resistor)V = 0.3A * 3.0ΩV = 0.9V
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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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