Question

A car battery with a $12V$ emf and an internal resistance of $0.04\Omega$ is being charged with a current of $50A$.The potential difference $V$ across the terminals of the battery is:

• A. $10V$
• B. $12V$
• C. $14V$
• D. $16V$

Answer 1

The correct option is C $14V$

Given,

$\epsilon =12V$

$r=0.04\Omega$

$I=50A$

The potential Difference across the terminal is $V$

$V=IR$

Here,

$I=\frac{E}{R+r}$

$I(R+r)=E$

$IR+Ir=E$

Substitute $V=IR$ in above equation

$V+Ir=E$

$V=E-Ir$

As Battery is charging then current direction will be reverse Therefore,

$V=E-(-I)r$

$v=E+Ir$

Now By putting all the above in above equation,

$V=12+(50\times 0.04)$

$V=12+2=14V$

Option (C) is correct option