Resistance is the measure of difficulty of passing an electric current through a material (measured in ohms).
If the material is rubber it has a very high resistance.
If the material is copper it has a very low resistance.
To visualise resistance scientists have found that a `250mm` length of graphite pencil should have `1` unit of resistance (`1` ohm)
NOTE: Don't forget to sharpen both ends
Another way of looking at resistance is to consider the following:
There is less resistance in Tank A and it will empty a lot faster than Tank B.
So too in terms of pipes.
There is less resistance in Pipe A and therefore flow will be a lot faster through it than Pipe B.
Also, there is less resistance in copper than rubber in electron flow:
Another way of thinking about resistance is hair getting stuck in a pipe.
Resistance `=` Hair