The emf of a cell of internal resistance $2 \ \Omega$ is measured using a voltmeter of resistance $998 \ \Omega$. The error in the emf measured is (in $\%$)

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

If each resistor in the given figure is $9\, \Omega$,then the reading of the ammeter is .............. $A$.

In the given circuit,for maximum power to be transferred from a battery with an internal resistance of $4\, \Omega$,what should be the value of $R$ in $\Omega$?

An electric kettle has two heating coils. When the first coil is switched on, the tea boils in $6$ minutes. When the second coil is switched on, it boils in $8$ minutes. If both coils are connected in series and switched on, how long will it take for the tea to boil?

$A$ circuit containing five resistors is connected to a battery with a $12 \,V$ emf as shown in the figure. The potential difference across the $4 \,\Omega$ resistor is ........... $V$.