Electric charge is generated by the transfer of electrons so, to understand the concept of electric charge, we must first understand electrons. 

The electron e- is a subatomic particle with a negative charge; its charge is also known as the elementary charge. We use the word “elementary” when describing these particles because we are unsure whether or not they’re made of other components. In other words, these subatomic particles are the smallest known components of matter in the universe. The other elementary particles are protons (positively charged particles) and neutrons (neutrally charged particles).

The electrical charge indicates the extent of a body’s electron surplus or deficiency. 

Electrical charge image of positively and negatively charged objects attracting one another. The positive object is a red circle with a plus sign. The negatively charged object is a blue circle with a minus sign.
Positively and negatively charged objects attract one another. | Image: Wikimedia Commons

2 Types of Electrical Charge

There are two types of electrical charge: positive and negative electric charges. If an object is positively charged, it is electron deficient. If an object is negatively charged, it has an excess of electrons. Of course, an object can also be neutrally charged, in which case there is neither an excess nor a deficiency of electrons. In other words, an electrically neutral object has no charge. 

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How Does Electrical Charge Work?

You can easily observe electrical charges in everyday life. For example, if you rub a balloon on your hair, the balloon becomes negatively charged (i.e. it has an electron surplus) and your hair becomes positively charged (i.e. it has an electron deficiency). Because of the charge difference — remember, opposites attract — your hair is attracted to the balloon and starts to stand up to reach it.

The electric charge has the symbol Q or q and the unit 1 C (one coulomb), named after the French naturalist Charles Augustin de Coulomb (1736-1806). A body has a charge of 1 C if it has an electron excess of 6,24 x 1018 electrons. This is the number of electrons that flow through the cross-section of a conductor in one second at a current of 1 A.

The electrical charge of bodies in our environment (charged spheres, electrical charging of people) is usually much less than one-thousandth of a coulomb.

Accordingly, an electron has a charge of 1C/(6,24⋅1018) = −1.6⋅10-19 C. This charge is also called the elementary charge, e

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How to Measure and Calculate Electrical Charge

The electric charge Q is specified as a multiple N of the elementary charge e:

Q = N * e

The electron with its electrical charge of −1.6⋅10-19 C has exactly the elementary charge -e, while the proton has the elementary charge +e.

Electric Charge: Crash Course Physics. | Video: CrashCourse


The Behavior of Electrically Charged Bodies

There is a simple relationship between charge and electric current strength. If a current of constant strength flows through an electric conductor, the following equation applies to the charge passing through a conductor cross-section:

Q=I⋅t where I is the electric current and t represents time.

This equation also results in the relationship mentioned above:

1 C = 1 A⋅1 s = 1 As

If a current of 1 A flows through an electrical conductor for 1 s, a charge of 1 C is transported through the cross-section of the conductor. With the transport of electrons, electrical charges are also transferred. This can lead to charge separation, charge sharing or charge equalization.


Electrical Charge vs. Electric Current 

electrical charge image illustrating how electric current flows in opposite directions depending on their charge.
A schematic showing the direction of electric current as opposite to those of the negative charge carriers in a conductor. | Image: Wikimedia Commons

Electric charge is the basis for generating electric current. The electric current, described by the formula I, is the directional movement or flow of electric charge. To generate electricity, you need two components:

  1. You need an electrical conductor that provides you with free charge carriers and connects all components with each other (an electrical circuit).
  2. You need a source that sets the charge carriers in a directed movement (voltage source).

The definition of the current intensity I as the amount of charge Q per time t leads to the following relationship:

I = Q/t

In summary, the current increases with the number of electrons moving through an object per time.

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