Physics 9702 · AS & A Level · Potential difference and power

Potential difference and power — practice question

A cell has an electromotive force (e.m.f.) of $6.0\,\text{V}$. Its internal resistance is negligible, and it is connected to a resistor. The potential difference (p.d.) across the resistor is also $6.0\,\text{V}$. Although the e.m.f. and the p.d. are equal in numerical value, they refer to different processes. Which statement about these different processes is correct?

  • AThe e.m.f. is the energy transferred from chemical energy to electrical energy in the cell and the p.d. is the energy transferred from electrical energy to thermal energy in the resistor.
  • BThe p.d. is the energy transferred from chemical energy to electrical energy in the cell and the e.m.f. is the energy transferred from electrical energy to thermal energy in the resistor.
  • CThe e.m.f. is the energy transferred per unit charge from chemical energy to electrical energy in the cell and the p.d. is the energy transferred per unit charge from electrical energy to thermal energy in the resistor.
  • DThe p.d. is the energy transferred per unit charge from chemical energy to electrical energy in the cell and the e.m.f. is the energy transferred per unit charge from electrical energy to thermal energy in the resistor.

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