Question

A battery has emf $4\text{V}$ and internal resistance $r$. When this battery is connected to an external resistance of $2\Omega$, a current of $1\text{A}$ flows in the circuit. How much current will flow if the terminals of the battery are connected directly?

• A. $1\text{A}$
• B. $2\text{A}$
• C. $4\text{A}$
• D. Infinite

Answer 1

The correct option is B $2\text{A}$


From figure,
$i=\frac{E}{R+r}$

$\therefore 1=\frac{4}{2+r}$

$\therefore r=2\Omega$

When terminals are connected directly there is short circuit and current flows during short circuit is given as:

$i_{SC}=\frac{E}{r}=\frac{4}{2}=2\text{A}$