JAMB - Physics (1979 - No. 20)
An electric cell has an internal resistance of 2 ohms. A current of 0.5A is found to flow when a resistor of 5 ohms resistance is connected across it. What is the electromotive force of the cell?
5 volts
3.5 volts
2.5 volts
1 volts
10 volts
توضيح
E.m.f. = I(R + r) = 0.5(2+5) = 3.5 volts