Chapter 17, Problem 1MCQ

When a battery with a significant internal resistance is part of a complete circuit, the voltage across its terminals is its (a) emf, (b) terminal voltage, (c) power output, (d) all of the preceding.

To determine

The voltage across the battery with internal resistance.

Answer to Problem 1MCQ

The voltage across the battery with internal resistance is $\left(\text{b}\right)\text{Terminal}\text{voltage}$.

Explanation of Solution

Terminal voltage is expressed as,

$V_T=\epsilon -Ir$………………………………………………………………………. (1)

Here, $V_T$is the terminal voltage, $\epsilon$is the emf, $I$is the current in the circuit and $r$is the internal resistance.

Conclusion:

Voltage across the battery when it is not connected to a circuit is referred as emf. Therefore, option (a) is incorrect.

Power output doesn’t correspond to the voltage of the battery. Therefore, option (c) is incorrect.

When the battery has internal resistance, the total voltage across its terminals is equal to the terminal voltage given by equation (1). Therefore, option (b) is correct.