Solar Energy Water and Power — 14 July 2013

Common electrical units are Power (P), Current (C), Voltage (E), and Resistance (R).  Here is how these are measured and what they mean.


A watt is a unit of electrical power or energy.  A single watt of energy is equal to one ampere of current flowing under the force of one volt.


An ampere is a measurement unit of current.  One ampere is the current which one volt can send through a resistance of one ohm.


Voltage is a unit of electrical potential or motive force and is measure in “volts”.  A single volt represents the potential required to send one ampere of current through one ohm of resistance.


An Ohm is a unit of resistance. One ohm is the resistance impeding the passage of one ampere when impelled by one volt.

Water Analogy

Since we can’t see watts, voltage, and amperes with our eyes; I’ve found it useful to make an analogy of all these electrical units with the flow of water through a pipe.  The analogy makes the following relationships:

Water pressure = Voltage (E)

Flow rate = Current (I)

Pipe diameter = Resistance (R)

By increasing the diameter of a pipe, the flow rate increases.  Likewise, reducing the electrical resistance (R) will allow more current (I) to flow.  The same is true if you increase the water pressure.  Increasing the electrical voltage (E) also increases the electrical current (I).

Common Electrical Formulas and Relationships

Here are some relationships (formulas) for calculating electrical units (i.e. how to calculated watts)




About Author


(0) Readers Comments

Leave a Reply

Your email address will not be published. Required fields are marked *