Electrical energy


Content – Forms of energy



Electrical energy – Electrical current

Electrical current is movement of electrically charged particles, which may be electrons or ions.

The movement of electrically charged particles will in normal day life mean electricity that we receive through cables from the power plant or radio waves moving through air converted to other forms of energy by our home appliances.

Electrical current is measured in Ampere (A), which is a measure of movement of electrical charge during a certain time.The movement occur when there exist a differential potential between two locations connected with an electrical leader (within an electrical circuit).

Electrical energy

Electrical energy is the combination of electric current (movement) and electrical potential that is delivered by a circuit.

Electrical energy – Electric fields

Electric fields are areas surrounding charged particles that exert force on other charged particles causing the particles to move and do work.

Electric fields can be compared to gravitational fields in that both fields are areas surrounding an object that are influenced by the object.

Positive charged particles create electric fields that repel other positive charged particles. Negative charged particles create electric fields that attract positive charged particles.


All matter is made up of atoms, and atoms are made up of particles, positive charged particles (protons), neutral charged particles (neutrons), and negatively charged particles (electrons). Electrons orbit around the centre of the atoms (nucleus). The nucleus is made up of neutrons and protons.

Illustration of carbon atom. (This text is displayed because your browser do not support SVG)



Many metals have certain electrons that are loosely attached to their atoms. If an electric field is applied electrons will move from one atom to another, thereby a current of electricity is created.

An ability of a substance to flow electrons (or conduct electricity) is its conductivity.

Since many metals have a high conductivity they are often used to transfer electricity. Copper is such a metal with a very high conductivity providing very little resistance to the movement of electrons.

Formula for electrical energy

Energy (Joule) = Power (Watt) x Time (Second)
Power (Watt) = Energy(Joule) / Time(Second)
1 Watt = 1 Joule / Second.

Electrical energy may be defined by the work (W) carried out or needed to move electrically charged particles.

W = UIt (Joule)
U = Differential potential (Volt)
I = current (Ampere) (Columb per second)
R = Resistanse (Ohms Ω)
t = time (second)

From the equation above we can derive the following equations that:


P (Power) = W/t = UIt/t = Ui (volts x ampere) (Watt)
P = R x I2
P = U2/R


I = P/U (ampere)
I = U/R
I = (P/R)1/2

Electrical potential

U = RI
U = P/I
U = (PR)1/


R = U/I (ohm`s law)
R= P/I
R = P/I2

Differential potential (Volt) measures how much electrical energy at a certain charge (certain number of electrons) that is transmitted (or needed to be transmitted) through a circuit. The number of electrons is measured by the unit Coulomb (1.6 x 1019 electrons).

1 Volt = 1 joule/Coulomb

1 Ampere is the electrical current needed to transport one colomb per second

1 Ampere = 1Coulomb/second

The electrical charge (Q) of an electron (negative) or proton (positive) is = 1,60217653× 10-19 Coulomb (C)

The unit of resistance (ohm) is the resistance between two points of a conductor when a constant potential difference of 1 volt, applied to these points, produces in the conductor a current of 1 ampere.