A battery of emf 20 V and internal resistance \( 2\,\Omega \) is connected to a resistor, if the current in the circuit is 1 A, find the terminal voltage of the battery.
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → 18 V
When a battery delivers a current I, part of its emf is lost across its own internal resistance r, so the terminal voltage is less than the emf.
\( V = \varepsilon - Ir = 20\,\mathrm{V} - (1\,\mathrm{A})(2\,\Omega) = 20\,\mathrm{V} - 2\,\mathrm{V} = 18\,\mathrm{V} \)