What are the factors on which the resistivity of a material depends?

$(i)$ Draw a circuit diagram to show how two resistors are connected in series.
$(ii)$ In a circuit,if two resistors of $5 \ \Omega$ and $10 \ \Omega$ are connected in series,how does the current passing through the two resistors compare?

What is meant by resistance?

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

$A$ conducting wire offers resistance to the flow of electrons because electrons repel each other in the wire.

$(a)$ In the circuit shown, connect a nichrome wire of length $L$ between points $X$ and $Y$ and note the ammeter reading.
$(i)$ When this experiment is repeated by inserting another nichrome wire of the same thickness but twice the length $(2L)$, what changes are observed in the ammeter reading?
$(ii)$ State the changes that are observed in the ammeter reading if we double the area of cross-section without changing the length in the above experiment. Justify your answer in both cases.
$(b)$ "Potential difference between points $A$ and $B$ in an electric field is $1\, V$." Explain the statement.