Question

A battery of an emf of 15 V is delivering power to an external load resistor R = 18 Ω. The terminal voltage of the battery is 12 V. What is the internal resistance of the battery?Group of answer choices1.50 Ω2.50 Ω3.50 Ω4.50 Ω5.50 Ω

Answer 1

The resistance of the battery is 4.50 Ω.

Given data:

The emf of battery is e=15 V.

The resistance of external load is R= 18 Ω.

The voltage of battery is V=12 V.

The current passed by the battery can be calculated as,

`\begin{gathered} I=(V)/(R) \\ I=\frac{12\text{ V}}{18\text{ }\Omega} \\ I=0.667\text{ A} \end{gathered}`

The internal resistance of the battery is given by,

`r=(e-V)/(I)`

Substitute the values in above equation,

`\begin{gathered} r=\frac{15\text{ V-12 V}}{0.667} \\ r=4.50\text{ }\Omega \end{gathered}`

Thus, the resistance of the battery is 4.50 Ω.