Question

A battery of emf $12V$ is connected to an external resistance of 20 $\Omega$ and it is found a potential difference of $10V$. The internal resistance of battery is

• A. 1$\Omega$
• B. 2$\Omega$
• C. 3$\Omega$
• D. 4$\Omega$

Answer 1

Answer: (D)

4$\Omega$

Given $R=20\Omega$

$IR=10V$

$E=12V$
$IR=10$

$I=0.5A$
$E=I[R+r]$

$24=R+r$

$r=4\Omega$