When we apply a voltage V across an electrical component, we get a current I. To a layman, resistance is simply the R in . It is measured in ohms (symbol Ω) by ohmmeters. It can also be calculated as the ratio.
If we continue with the water analogy, then voltage is analogous to the pressure that pushes water through a water hose. The rate of flow of water (which is analogous to the current) depends on the dimension and condition of the hose. Is it narrow or wide? Is it clean or choked with sand? Similarly, resistance of an electrical component depends on its dimension and material. It determines the magnitude of the current for a given voltage.
Again, let’s hear what the physicists have to add.