A cell of emf 12 V and internal resistance 1 ohm supplies a current of 2 A. The terminal potential difference is
- A. 12 V
- B. 14 V
- C. 10 V
- D. 2 V
Explanation
The lost volts inside the cell are I times r, that is 2 multiplied by 1, giving 2 V, so the terminal voltage is 12 minus 2, which is 10 V. This is why a car's headlights dim when the starter motor draws a very large current. Adding rather than subtracting gives the impossible 14 V.