Terminal voltage of a cell equals its EMF only when:
- A. No current flows
- B. Current is maximum
- C. Internal resistance is infinite
- D. Load resistance is zero
Explanation
The lost volts inside the cell are the current multiplied by the internal resistance, so only when the current is zero, that is on open circuit, does the terminal voltage rise to the full emf. This is why a high resistance voltmeter across an unloaded cell reads its emf. Short circuiting the cell does the opposite, making the current maximum and the terminal voltage nearly zero.