Ohm’s Law also makes intuitive sense if you apply it to the water-and-pipe analogy. If we have a water pump that exerts pressure (voltage) to push water around a ”circuit” (current) through a restriction (resistance), we can model how the three variables interrelate.
If the resistance to water flow stays the same and the pump pressure increases, the flow rate must also increase.
|Pressure = Increase||Voltage = Increase|
|Flow rate = Increase||Current = Increase|
|Resistance = Same||Resistance = Same|
If the pressure stays the same and the resistance increases (making it more difficult for the water to flow), then the flow rate must decrease:
|Pressure = Same||Voltage = Same|
|Flow rate = Decrease||Current = Decrease|
|Resistance = Increase||Resistance = Increase|
If the flow rate were to stay the same while the resistance to flow decreased, the required pressure from the pump would necessarily decrease:
|Pressure = Decrease||Voltage = Decrease|
|Flow rate = Same||Current = Same|
|Resistance = Decrease||Resistance = Decrease|
Review of Water-and-Pipe Analogy for Ohm’s Law
- With resistance steady, current follows voltage (an increase in voltage means an increase in current, and vice versa).
- With voltage steady, changes in current and resistance are opposite (an increase in current means a decrease in resistance, and vice versa).
- With current steady, voltage follows resistance (an increase in resistance means an increase in voltage).
Resource: Lessons in electric circuits , Volume I – DC