An electric bulb rated $500 \, W$ at $100 \, V$ is used in a circuit having a $200 \, V$ supply. Calculate the resistance $R$ to be connected in series with the bulb so that the power delivered by the bulb is $500 \, W$. (in $\Omega$)

The figure shows a circuit having eight resistances of $1 \Omega$ each,labelled $R_1$ to $R_8$,and two ideal batteries with voltages $\varepsilon_1=12 V$ and $\varepsilon_2=6 V$. Which of the following statement$(s)$ is(are) correct?
$(A)$ The magnitude of current flowing through $R_1$ is $7.2 A$.
$(B)$ The magnitude of current flowing through $R_2$ is $1.2 A$.
$(C)$ The magnitude of current flowing through $R_3$ is $4.8 A$.
$(D)$ The magnitude of current flowing through $R_5$ is $2.4 A$.

If the rheostat slider were to move from the extreme right to the far left,how will the reading of voltmeter $V_1$ change?

In the given circuit,the current through the $2\,\Omega$ resistance is ............ $A$.

The internal resistance of a $2.1\, V$ cell which gives a current of $0.2\, A$ through a resistance of $10\,\Omega$ is ............. $\Omega$.

Inside a superconducting ring,six identical resistors each of resistance $R$ are connected as shown in the figure. The equivalent resistance$(s)$: