In the given circuit,the current through $2 \ \Omega$ resistor is

$A$ heater is designed to operate with a power of $1000 \ W$ in a $100 \ V$ line. It is connected in combination with a resistance of $10 \ \Omega$ and a resistance $R$,to a $100 \ V$ mains as shown in the figure. For the heater to operate at $62.5 \ W$,the value of $R$ should be .................. $\Omega$.

$A$ current of $2\,A$ flows through a $2\,\Omega$ resistor when connected across a battery. The same battery supplies a current of $0.5\,A$ when connected across a $9\,\Omega$ resistor. The internal resistance of the battery is:

$A$ wire of cross-section area $A$,length $L_1$,resistivity $\rho_1$ and temperature coefficient of resistivity $\alpha_1$ is connected to a second wire of length $L_2$,resistivity $\rho_2$,temperature coefficient of resistivity $\alpha_2$ and the same area $A$,so that the wires carry the same current. The total resistance $R$ is independent of temperature for small temperature changes if (Thermal expansion effect is negligible):

$A$ cell of constant $e.m.f.$ is first connected to a resistance $R_1$ and then connected to a resistance $R_2$. If the power delivered in both cases is the same,then the internal resistance of the cell is:

$A$ battery of internal resistance $4 \,\Omega$ is connected to the network of resistances as shown. In order to give the maximum power to the network,the value of $R$ (in $\Omega$) should be