Why are alloys used to make standard resistors?

$V-I$ graphs for two wires $A$ and $B$ are shown in the figure. If both the wires are made of the same material and are of equal thickness,which of the two is of more length? Give justification for your answer.

Insulators like wood and rubber have a very low electrical resistance.

Explain the term resistance. Give its $SI$ unit of measurement.

State Ohm's law.

$(i)$ 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.