Question

A battery having $12$V emf and internal resistance $3\Omega$ is connected to a resistor. If the current in the circuit is $1$A, then the resistance of resistor and lost voltage of the battery when circuit is closed will be:

• A. $7\Omega ,7V$
• B. $8\Omega ,8V$
• C. $9\Omega ,9V$
• D. $9\Omega ,10V$

Answer 1

The correct option is C $9\Omega ,9V$

$I=\frac{V}{R}$

$=I=\frac{12}{3+R}$

$\Rightarrow 3+R=12$

$R=9\Omega$

Terminal voltage $=E-I$

$=12-3\times 1$

$=12-3=9V$

Answer is $(9,9)$