Of the following graphs,the one that correctly represents the $I-V$ characteristics of an 'Ohmic device' is:

Explain the statement: "$V \to I$ relation is not always a one-one function."

The voltage $V$ and current $I$ graph for a conductor at two different temperatures $T_1$ and $T_2$ are shown in the figure. The relation between $T_1$ and $T_2$ is

$A$ potential difference of $10 \,V$ is applied across a conductor of $1000 \,\Omega$. The number of electrons flowing through the conductor in $300 \,s$ is ..........

What conclusion can you draw from the following observations on a resistor made of alloy manganin?

$I (A)$	$V (V)$	$I (A)$	$V (V)$
$0.2$	$3.94$	$3.0$	$59.2$
$0.4$	$7.87$	$4.0$	$78.8$
$0.6$	$11.8$	$5.0$	$98.6$
$0.8$	$15.7$	$6.0$	$118.5$
$1.0$	$19.7$	$7.0$	$138.2$
$2.0$	$39.4$	$8.0$	$158.0$

State and explain Ohm's law.