$A$ piece of wire of resistance $R$ is cut into five equal parts. These parts are then connected in parallel. If the equivalent resistance of this combination is $R'$,then the ratio $R/R'$ is

Name a device that helps to maintain a potential difference across a conductor.

When a $12\, V$ battery is connected across an unknown resistor,there is a current of $2.5\, mA$ in the circuit. Find the value of the resistance of the resistor.

The values of current $I$ flowing in a given resistor for the corresponding values of potential difference $V$ across the resistor are given below -

$I$ (amperes)	$0.5$	$1.0$	$2.0$	$3.0$	$4.0$
$V$ (volts)	$1.6$	$3.4$	$6.7$	$10.2$	$13.2$

Plot a graph between $V$ and $I$ and calculate the resistance of that resistor.

$A$ battery of $9 \, V$ is connected in series with resistors of $0.2 \, \Omega$,$0.3 \, \Omega$,$0.4 \, \Omega$,$0.5 \, \Omega$,and $12 \, \Omega$ respectively. How much current (in $A$) would flow through the $12 \, \Omega$ resistor?

Draw a schematic diagram of a circuit consisting of a battery of three cells of $2\, V$ each,a $5\,\Omega$ resistor,an $8\,\Omega$ resistor,and a $12\,\Omega$ resistor,and a plug key,all connected in series. Include an ammeter to measure the current through the resistors and a voltmeter to measure the potential difference across the $12\,\Omega$ resistor. What would be the readings in the ammeter and the voltmeter?