The resistivity of a material does not change if:

Electrical resistivity of a given metallic wire depends upon

$(i)$ Name and state the law that gives the relationship between the current through a conductor and the potential difference across its two terminals. Also,express this law mathematically.
$(ii)$ Draw the $V-I$ graph for this law. Justify your answer.
$(iii)$ Write the name and use of the circuit components whose symbols are given below:
$(a)$ $A$ resistor with an arrow through it.
$(b)$ $A$ circle with a dot inside,connected to two lines.

The amount of charge passing through a cell in $4 \, s$ is $12 \, C$. Find the current supplied by the cell. (in $, A$)

$1 \, \mu A = \ldots \ldots \ldots \, A$

Define one ampere.