Fundamentals of Electricity Concepts
Historical Figures in Electricity
Joseph Thomson
Inventor of the mass spectrometer, discovered the electron and isotopes.
Thales
Observed electrical phenomena by rubbing amber with a cloth and noted that the bar attracted objects.
Otto von Guericke
Observed that repulsion occurred between electrified bodies after they had been attracted. He devised the first electrostatic generator, a sulfur ball, and produced sparks, which led him to speculate about the electrical nature of lightning.
Pieter van Musschenbroek
Performed several experiments on electricity. He investigated whether water enclosed in a container could retain electrical charges. During one experiment, one of his assistants touched the container and received a strong electric shock. This led to the discovery of the Leyden jar.
Fundamental Electricity Concepts
Electricity
Category of physical phenomena caused by the existence and interaction of electric charges.
Forms of Electrifying Bodies
Bodies become electrified by the loss or gain of electrons. If a body is positively charged, this does not mean it has an excess of protons.
Friction
By rubbing two electrically neutral bodies (where the number of electrons equals the number of protons), both become charged, one positively (+) and the other negatively (-).
Contact
A body can be charged by touching another previously charged body. Both bodies end up with the same type of charge. For example, if a neutral body touches a positively charged body, the neutral body also becomes positively charged.
Induction
An electrically charged body can attract another body that is neutral. When a charged body is brought closer to a neutral body, an electrical interaction is established between the charges of the first body and the neutral body.
Coulomb’s Law
States that the force (F) between two point charges (Q1 and Q2) is directly proportional to the product of their charges and inversely proportional to the square of the distance separating them.
Unit of Electric Charge
The Coulomb (C) is the unit of electric charge. It is defined as the amount of charge that passes through a section of a conductor in one second when the current is one ampere.
Potential Difference
What drives the current through a circuit? It is the potential difference. When we have two bodies, one with a positive charge (+) and another with a negative charge (-), and connect them through a conductor, electric charge flows from the positively charged body to the negatively charged body. This flow of charge is the electric current.
Electric Current Flow
Flow of electric charges through a section of a conductor due to a potential difference.
Ohm’s Law
The intensity of the electric current flowing through a given conductor is directly proportional to the applied potential difference across its ends and inversely proportional to the conductor’s resistance.
Electrical Resistance
Opposition that a conductor presents to the passage of electric current or electron flow.
Electric Potential
Electric potential is a scalar quantity, like energy. It is defined as the potential energy possessed by a unit of electric charge at a specific point.
Electromotive Force (EMF)
Measures the amount of energy provided by an element or generated electrical current. A device that has the ability to maintain the potential difference between two points is called a source of electromotive force.
Electric Current
Electric current is the rate of flow of electric charge passing through a point P in an electrical conductor, or the amount of electric charge flowing through a conductor in unit time.
Parallel Connection
In a parallel connection, components (like resistors) are joined at their terminals, connecting them across the same two points or nodes, typically connected to the power or voltage source.