What's the difference between Volts, Watts, and Amps?23 Mar 2016
In a world full of technology and electronics, we are often bombarded with terms that we seldom understand. Three terms that are thrown in front of us across all electronic products we purchase today are volt (V), watt (W), and amp (A). We see them listed everywhere - but what do they mean? Let me break these down for you.
I like to explain technical topics using every day metaphors that everyone understands. I find this leaves little room for confusion and allows people to move on and learn at an accelerated rate. In the case of electrical units, let's use the well-known garden hose as our metaphor of choice.
Let's start with volts (V).
The volt is a measure of electric potential - the energy that could be released if the current was allowed to flow. Under our garden hose metaphor, volts can be equivocally compared to water pressure, or, the potential that the hose has, should the current be allowed to flow.
Let's say we have a simple garden hose equipped with a spray nozzle. The nozzle can be either turned on or off, but the main faucet the hose is connected to is always turned on. Under this circumstance, the water pressure within the hose, whether or not the hose nozzle is open, remains the same. Now, think of the water pressure in terms of volts in a house, and think of the nozzle on the end of the hose in terms of a lightbulb. As long as there is power coming into the house, the voltage on the line remains the same whether or not the lightbulb is turned on.
In other words, the electric potential of the line remains constant at 120 volts (typical US home), regardless of any current flowing. Just like the water pressure (PSI) in the hose remains constant whether or not water is flowing out of the nozzle.
V = W / A
Next, amps (A)
Amps (A) or Amperes, are used to express the flow rate of electric charge. Going back to our garden hose metaphor, we can think of amps as the flow rate of water through the hose (gallons per minute). Referring back to volts and potential, if the hose nozzle is turned off, amps drop to 0, but voltage (electric potential) remains.
Amps are typically used to determine the current draw of appliances, and the gauge of wire required for a specific circuit within a home. The higher the calculated amperes, the thicker the gauge required to support the higher rate of flow.
A = W / V
A watt (W) is simply a unit of power. It can be used to express the rate of energy conversion or transfer with respect to time. Now this, may sound a lot like amps, but in our garden hose example, think of it as how quickly we can fill up a bucket with water from the hose. It is also the product of volts and amps - expressed as the rate at which work is done when one ampere (A) of current flows through the line with one volt (V) of electric potential.
To conclude, volts are the water pressure, amps are the flow rate, and watts are the rate at which we can fill a bucket with water.