How many times have you seen alightbulbprinted with “100W/120V” and wondered how the two units ofelectricityrelate?
Are watts and volts basically the same thing?
Can the two be used interchangeably?
The Spruce / Hilary Allison
Difference Between Watts and Volts
Watts and volts are not independent of each other.
Watts cannot exist without volts since they are the product of a combination of volts and amps.
Hydraulic Analogy
The hydraulic (water) analogy is a common method of explaining electrical terms.
Water flow within a closed-system pipe, or circuit, is compared to electrical flow.
What Are Volts?
In 1800, Volta invented a precursor of the electric battery called the Voltaic Pile.
Made of alternating zinc and copper discs, the Voltaic Pile produced a weak electric current.
What Are Amps?
The letter “A” is the symbol for amperes or amps.
Volume is quantity, not speed.
A lightning strike is about 20,000 amps.
A watch may draw one-millionth of an amp.
Household electrical cables typically are rated for 15 amps or 20 amps.
What Are Watts?
A watt describes the rate of power flow.
The letter “W” is the symbol for watt or watts.
Watts are derivedfrom the formula V (volts) x A (amps)= W (watts).
Think of watts not in terms of strength or capacity but speed or rate.
What Are Ohms?
Ohms indicate electrical resistance.
The Greek symbol for omega, resembling a downward horseshoe, also denotes ohms.
An analogy often used is traveling and travel rate.
As if you told a friend:
You’ve given the friend some information, but it’s incomplete.
There is no context.
How can you develop the perfect statement that takes both factors into account?
With the car, rate is equal to distance divided by time.
Inelectrical systems, amperage and voltage are useful sets of information.
One volt equals 0.001 kilowatts (kW) or 1000 watts per hour.
120 watts is certainly enough to shock a person.
It can power a small appliance but it’s not powerful enough for a large television or a computer.
Higher voltage means more power, and higher watts mean more power.
But it’s a moot question to ask whether volts or watts are more powerful.
By nature, increasing one would make it more powerful than the other.
Higher watts mean that more electricity is used.
For example, a100-watt LED lightbulbuses significantly less electricity than a 750-watt microwave oven.
Resolution 2 of the 41st CIPM (1946) / Definitions of electric units.
International Bureau of Weights and Measures / Bureau international des poids et mesures.
Unit 4: Energy Through Our Lives Part II.University of Wisconsin, Stevens Point
