What are the factors on which the resistance of a conductor depends?

In an electric circuit,state the relationship between the direction of conventional current and the direction of flow of electrons.

Define electric current and state its $SI$ unit. With the help of $Ohm's$ law,explain the meaning of $1$ ohm resistance.

What is the commercial unit of electric energy?

$A$ cylindrical conductor of length $l$ and uniform area of cross-section $A$ has resistance $R$. Another conductor of length $2l$ and resistance $R$ of the same material has area of cross-section:

Find out the following in the electric circuit given in the figure:
$(a)$ Effective resistance of two $8\,\Omega$ resistors in the combination.
$(b)$ Current flowing through the $4\,\Omega$ resistor.
$(c)$ Potential difference across the $4\,\Omega$ resistor.
$(d)$ Power dissipated in the $4\,\Omega$ resistor.
$(e)$ Difference in ammeter readings,if any.