# Water-and-Pipe Analogy for Ohm’s Law

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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

1. With resistance steady, current follows voltage (an increase in voltage means an increase in current, and vice versa).
2. With voltage steady, changes in current and resistance are opposite (an increase in current means a decrease in resistance, and vice versa).
3. With current steady, voltage follows resistance (an increase in resistance means an increase in voltage).

Resource: Lessons in electric circuits , Volume I – DC