Joule vs. Watt — What's the Difference?
By Tayyaba Rehman — Updated on August 25, 2023
Joule is a unit of energy, while watt is a unit of power.
Difference Between Joule and Watt
Table of Contents
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Key Differences
Joule represents energy, and it is the amount of work done when a force of one newton moves an object one meter. Watt, on the other hand, signifies power and indicates the rate at which energy is transferred or converted per unit of time.
In the metric system, joule is symbolized by "J," indicating the amount of energy either consumed or produced. Watt is represented by "W" and signifies the rate at which work is done or energy is transferred.
If we take a simple analogy, joule could be compared to the water in a tank, indicating its quantity. Watt would then represent the speed at which water flows out of the tank.
Joule, being a measure of energy, can accumulate over time. For example, a battery can store a certain number of joules. Watt illustrates how quickly the stored joules in that battery can be used or drained.
Understanding the difference between joule and watt is crucial in various applications. A light bulb, for instance, may use energy at a rate of 60 watts, but the total energy it consumes (in joules) will depend on how long it is turned on.
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Comparison Chart
Nature
Unit of energy
Unit of power
Symbol
J
W
Relation
Amount of energy
Rate of energy transfer
Derived From
Force and displacement
Joules per second
Example
Energy stored in a battery
Power consumption of an appliance
Compare with Definitions
Joule
Joule quantifies the amount of energy transferred.
The device required 100 joules to operate for a minute.
Watt
Watt represents the rate of energy transfer.
The bulb uses 60 watts of power.
Joule
Joule is a unit of work or energy.
He expended 500 joules of energy lifting the weight.
Watt
The watt (symbol: W) is a unit of power or radiant flux. In the International System of Units (SI), it is defined as a derived unit of (in SI base units) 1 kg⋅m2⋅s−3 or, equivalently, 1 joule per second.
Joule
Joule is equivalent to the energy transferred when one newton of force moves an object one meter.
To lift this object, 300 joules of energy was used.
Watt
Watt is equivalent to one joule per second.
The machine operates at 100 watts, consuming 100 joules every second.
Joule
Joule can be used to measure electrical, mechanical, thermal, or other types of energy.
The chemical reaction released 1000 joules of thermal energy.
Watt
Watt can describe how fast energy is consumed or generated.
The generator produces 500 watts of power every hour.
Joule
Joule, in terms of electricity, is equal to the energy transferred when one coulomb of charge passes through a potential difference of one volt.
The circuit's energy output was measured to be 150 joules.
Watt
Watt, in electrical terms, is the power developed when one volt of potential difference drives a current of one ampere.
The device draws 2 amperes at 230 volts, resulting in 460 watts.
Joule
The International System unit of electrical, mechanical, and thermal energy, equal to the work done when a force of one newton acts through a distance of one meter, and also equal to the work done when a current of one ampere is passed through a resistance of one ohm for one second.
Watt
Watt is used to quantify power in electrical systems.
The electric motor has a power rating of 1500 watts.
Joule
The joule ( jowl, jool; symbol: J) is a derived unit of energy in the International System of Units. It is equal to the energy transferred to (or work done on) an object when a force of one newton acts on that object in the direction of the force's motion through a distance of one metre (1 newton-metre or N⋅m).
Watt
An SI-derived unit of power equal to one joule per second. See Table at measurement.
Joule
In the International System of Units, the derived unit of energy, work and heat; the work required to exert a force of one newton for a distance of one metre. Equivalent to one watt of power for a duration of one second. Symbol: J
Watt
A unit of power equal to 1 joule per second; the power dissipated by a current of 1 ampere flowing across a resistance of 1 ohm
Joule
A unit of work which is equal to 107 ergs (the unit of work in the C. G. S. system of units), and is equivalent to one watt-second, the energy expended in one second by an electric current of one ampere in a resistance of one ohm; also called the absolute joule. It is abbreviated J or j. The international joule is slightly larger, being 1.000167 times the absolute joule. The absolute joule is approximately equal to 0.737562 foot pounds, 0.239006 gram-calories (small calories), and 3.72506 x 10-7 horsepower-hours, and 0.000948451 B.t.u.
Watt
The SI unit of power, equivalent to one joule per second, corresponding to the rate of consumption of energy in an electric circuit where the potential difference is one volt and the current one ampere.
Joule
A unit of electrical energy equal to the work done when a current of one ampere passes through a resistance of one ohm for one second
Watt
In the International System of Units, the derived unit of power; the power of a system in which one joule of energy is transferred per second. Symbol: W
Joule
English physicist who established the mechanical theory of heat and discovered the first law of thermodynamics (1818-1889)
Watt
A unit of power or activity equal to 107 C.G.S. units of power, or to work done at the rate of one joule a second. An English horse power is approximately equal to 746 watts.
Watt
Scottish engineer and inventor whose improvements in the steam engine led to its wide use in industry (1736-1819)
Common Curiosities
What is a joule in simple terms?
A joule is a unit that measures energy or work done.
How is watt related to joule?
A watt represents the rate of energy transfer, with one watt being equal to one joule per second.
How does a watt differ from a kilowatt?
A kilowatt is 1,000 watts; it's a larger unit of power.
Why is joule important in physics?
Joule quantifies energy, which is a foundational concept in various physical phenomena and applications.
Is watt a measure of how fast energy is used?
Yes, watt quantifies the rate at which energy is consumed or produced.
How can I convert joules to watts or vice versa?
You cannot directly convert them since joules measure energy and watts measure power. However, if you know the time, watts = joules/time (in seconds).
Can I equate joule to calories or BTUs?
Yes, joules can be converted to other energy units like calories (1 calorie = 4.184 joules) or BTUs.
Can we say joule is a measure of effort?
In a way, yes. Joule measures the energy or work required for a task.
If an appliance is rated 100 watts, how much energy does it use in an hour?
It would use 100 joules every second, totaling 360,000 joules or 360 kJ in an hour.
Does a higher wattage device use more joules?
Over the same time period, a higher wattage device would use more joules since it consumes energy at a faster rate.
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Written by
Tayyaba RehmanTayyaba Rehman is a distinguished writer, currently serving as a primary contributor to askdifference.com. As a researcher in semantics and etymology, Tayyaba's passion for the complexity of languages and their distinctions has found a perfect home on the platform. Tayyaba delves into the intricacies of language, distinguishing between commonly confused words and phrases, thereby providing clarity for readers worldwide.
