Question

A rheostat and an ammeter are connected in series to a battery if of 0.2-ohm internal resistance. when the rheostat is adjusted to 10 ohms, the ammeter reads 5 amperes. The ammeter reading drops to 3 amperes, when the rheostat is adjusted to 18 ohms. what is the emf of the battery?

with solutions pls

Answer 1

By combining the voltage drop across the rheostat with the voltage drop across the internal resistance, the emf of the battery can be calculated. The voltage drop across the rheostat in this scenario is 50 volts when the rheostat is set to 10 ohms and the ammeter reads 5 amperes. Ohm's law is used to compute the voltage drop across the internal resistance (0.2 ohms * 5 amperes = 1 volt). We can calculate the battery's emf by adding these two volts, which give us the answer 51 volts.