How does the resistance increase when the length of the conductor increases? Why does it decrease if the cross sectional area increases?
This can be simply explained as below.
when you have longer length of wire, the current has to travel more distance, more the distance higher the number of obstacles it faces through its path. Therefore resistance increases with the length.
When cross sectional area increases the space of the elctrons to travel increases(simply explained). Therefore less amount of obstacles for the current. Therefore when area increases the resistance decreases.