Question

The battery in the diagram is to be charged by the generator $G$. The generator has a terminal voltage of 120 Volts when the charging current is 10 Amperes. The battery has an emf of 100 Volts and an internal resistance of 1 Ohm. In order to charge the battery at 10 Amperes charging current, the resistance $R$ should be set at :

• A. $0.1\Omega$
• B. $0.5\Omega$
• C. $1.0\Omega$
• D. $5.0\Omega$

Answer 1

The correct option is C $1.0\Omega$

The generator has a terminal voltage of 120 volts when the charging current is 10 amperes. Hence,
E = V + Ir = 120+ 10(1) = 130V
Hence, in circuit
$R=\frac{E-V}{I}$
$R=\frac{130-120}{10}=1\Omega$