Electricity Fundamentals: Coulomb, Field, Current & EMF

Coulomb

Coulomb: The forces with which two point charges attract or repel are equal and opposite and have the direction of the line joining them. Their magnitudes are directly proportional to the product of the magnitudes of the charges and inversely proportional to the square of the distance that separates them.

Electric Field Intensity

Intensity of the electric field: The intensity of the electric field created by a charge q at a point P is the force exerted on a unit positive charge (+1 C) placed at that point.

Potential Difference

Potential difference: Between two points, it is the work done by electric field forces to bring a unit positive charge from the first point to the second. It can be expressed as the work per unit charge required to move the charge between those points.

Current Intensity

Current intensity: The measure of the amount of charge q that passes through a cross-section of a conductor per second.

Ohm's Law

Ohm's Law: Experiments show that, for many conductors, the current through the conductor and the potential difference across its ends are directly proportional, provided temperature and other physical conditions remain constant.

Electrical Resistor

Electrical resistor: Represents the opposition to electron motion within a conducting material; electrons collide with each other and with the lattice of metal ions. Resistance depends on factors such as:

• 1) length of the wire
• 2) type of metal of the wire

EMF (Fem)

Fem (EMF): The electromotive force is the potential difference provided by a generator that drives electrons to circulate around the circuit without interrupting the current flow.

Electrification

Electrification:

• By induction: Bringing a charged body near a neutral conductive body causes redistribution of charges without direct contact.
• By contact: Touching a neutral conductor with an electrically charged body transfers charge to or from the conductor.

Superposition of Forces

Superposition of forces: To calculate the total force that two or more charges exert on another charge q, we must take into account that:

1. The effect of each charge is independent of the existence of the others.
2. The total force is calculated by adding all forces (vector sum).

Electric Field

Electric field: The disturbance created by an electric charge in the surrounding space. This perturbation means that if we place a charge in this region it will experience a force.

Electricity

Electricity: It is the organized movement of electrons within a conductor. This movement is driven by a potential difference that provides energy to the electrons.

Generators

Generators: Devices that produce a potential difference and give the electrons the energy necessary for an organized movement along conductors.

Receivers

Receivers: These are devices that use electric current to operate different types of equipment.

FCEM

FCEM: The potential difference across the terminals of a motor is equal to the sum of the voltage required for operation, commonly referred to as the counter electromotive force (counter EMF).