Unit of Energy

Energy, in simple terms, can be defined as the capacity for doing work. It can occur in kinetic, potential, electrical, chemical, nuclear, thermal, and other forms. It is classified as renewable energy and non-renewable energy. Further, in this article, we shall discuss the various units of energy.

Table of Contents

What is the SI Unit of Energy?

Following is the table of SI units:

SI unit joules

Interestingly, the name of this international unit is kept in honour of James Prescott Joule, a British physicist whose works contributed to the establishment of the energy concept. When we look at the unit in fundamental terms, 1-N.m is equal to 1 joule and, in terms of SI base units, it can be represented as:

\(\begin{array}{l}1\,J=1\,kg(\frac{m}{s})^{2}=1\frac{kg.m^{2}}{s^{2}}\end{array} \)

What is the CGS Unit of Energy?

Following is the table of the unit in the CGS system:

CGS unit erg

One erg is equal to 10-7 J. An erg is defined as the amount of work done by the force of one dyne at a one-centimetre distance.

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What is the Unit Of Energy In MKS System?

Following is the table of the unit in the MKS system:

MKS unit joule

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Units of Energy List

Energy units can be preceded by various factors, and there are usually different units for measuring energy. Some common units include:

  1. British thermal unit (BTU)
  2. Kilowatt-hour (kWh)
  3. Calorie
  4. Electronvolts (eV)
  5. Hartree (the atomic unit of energy)
  6. Rydberg units
  7. Barrel of oil

Energy Conversion

Following is the table with the energy conversion list:

Unit Joule Calorie BTU Kilowatt-hour
Joule 00 0.2390 0.000948 2.77778E-07
Calorie 4.187 00 0.00397 1.16279E-06
BTU 1055 252 00 0.000293
Kilowatt-hour 3.6E6 8.6E5 3412 00

Commercial Unit of Energy

Kilowatt-hour is the commercial unit of energy.
When large quantities of energy are expressed, the SI unit of energy becomes small. Therefore, the commercial unit is used.

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Frequently Asked Questions – FAQs


What is the relation between power and energy?

The relation between power and energy is that power has energy units divided by time.
The unit of power is watts.
Unit of energy is joules
1 watt = 1 Joule/1 second


What happens to energy when force and length is doubled?

When force and length is doubled, energy will increase by 4 times.
The relationship between energy, force, and distance is given as:
Energy = force x distance

E = f x d
Given that,
E = 2 f x 2 d
Therefore, E = 4fd.


What is the relation between commercial and SI unit of energy?

The commercial unit of energy is 1 kWh. One kilowatt-hour is defined as the amount of energy consumed by a device in one working hour at a constant rate of one kilowatt.
The SI unit of energy is joule.
Therefore, the relationship between commercial and SI units of energy is:
1 kWh = 1kW x 1h = 1000W x 1h = 1000(J/s) x 3600 s = 3.6 x106 J


One unit of electrical energy is equal to how many joules?

One unit of electrical energy is equal to 3.6 × 106 joules.


When will a spring have maximum potential energy?

Spring will have maximum energy when it is either pulled out or compressed.


1 joule is equal to how many ergs?

1 joule is equal to 107 ergs.


Give examples of potential energy.

Following are examples of potential energy:

  • Gravitational potential energy
  • Elastic potential energy

List the different forms of kinetic energy.

Following are the different forms of kinetic energy:

  • Translational kinetic energy
  • Vibrational kinetic energy
  • Rotational kinetic energy

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