An electric field is defined as the region surrounding an electrically charged object. Within this field, any other charged objects will experience an electromagnetic force.
Electric field strength, also known as electric field intensity, measures the magnitude of this field. This can be observed by placing a unit positive charge in the vicinity of a charged object.
If the object is positively charged, the unit charge experiences a repulsive force, pushing it away from the object. The imaginary path along which this unit positive charge moves is referred to as the line of force.
Conversely, in the field of a negatively charged object, the unit positive charge experiences an attractive force, pulling it closer. In this case, the path taken by the positive unit charge is also referred to as the line of force.
If the object is positively charged, the unit charge experiences a repulsive force, propelling it away from the object. This behavior is reminiscent of the way current flows in an electrical circuit. The trajectory along which this unit positive charge moves is known as the line of force.
Conversely, within the field of a negatively charged object, the unit positive charge experiences an attractive force, drawing it closer, much like how voltage creates a potential difference enticing electric charges to move across a circuit.
In this case, the path traversed by the positive unit charge is also termed the line of force.
Quantifying the Electric Field
The strength of the electric field at a point in space is determined by the force acting on a unit positive charge at that point. The interaction of a charged object within another object’s electric field is dictated by Coulomb’s law.
Imagine a charged object with a charge of Q1 Coulombs, and a unit positive charge is positioned r meters away from Q1‘s center.
So, as per Coulomb’s law, the force experienced by the unit positive charge is,
The force experienced by the unit positive charge measures the electric field of Q1 at the point where the unit positive charge is positioned. This force vector is represented by 
. Hence, the term E is recognized as electric field intensity or electric field strength.
Now, let’s place another charged object, Q2, at the same point where the unit positive charge was placed.
As per Coulomb’s law, two positively or negatively charged objects repel each other, while two oppositely charged objects attract each other with force 
.
This attraction or repulsion force can be written as:
Therefore, the vector of the electric field, , signifies how strongly an electric charge is repelled or attracted by the charge that created the electric field.
The Direction of an Electric Field
The direction of an electric field is determined by the movement of an imaginary unit positive charge within the field.
Depending on the charge that created the field, the unit charge may either move closer or farther away due to the electrostatic force of the field.
This directional movement of the unit positive charge within the field is considered the direction of the electric field, thus making an electric field a vector quantity.
The Static Electric Field
It is a well-known fact that there exist two types of charge in nature: positive and negative. In the case of a positive charge, there is primarily a deficiency of electrons, while a negative charge has an excess of electrons.
A basic demonstration of electric charge and the static electric field can be observed using a dry comb and small paper pieces. If you comb your dry hair a few times and then bring the comb close to the paper pieces, you will notice that the paper pieces are attracted to the comb.
This occurs because the friction between the comb and hair causes a transfer of electrons, resulting in one of them becoming positively charged and the other negatively charged. The neutral paper, having no charge, is attracted to the comb.
An attractive force exists between a charged particle and a neutral particle. Further observation reveals that a repulsion occurs between two similarly charged particles, and an attraction occurs between two oppositely charged particles. This interaction is a result of the field created by the charged particle.
To comprehend this concept, imagine a type of glowing light bulb. Consider the bulb as the charged particle, and the visible light can be likened to the static electric field. Just like light, the field’s intensity is greatest near the source and diminishes as we move further away.
From another perspective, a static electric field can be characterized as a power-intense space where work is done or required in the presence of an electrically charged particle, depending on the nature of that charged particle.
Practical Applications of Electric Fields
The understanding and control of electric fields are pivotal in various fields such as electronics, telecommunications, and electrical engineering.
Electric fields influence the operation of many devices and systems, including induction motors, dipole antennas, and electric power transmission lines.
The History of Electrical Fields
The discovery and understanding of electric fields have been a progressive journey spanning centuries. One of the most notable figures in this pursuit was Michael Faraday, an English scientist whose work in the mid-19th century was instrumental in developing the concept of the electric field. His experiments led to the idea that electric charges create invisible fields around them, influencing other charges.
In the late 19th century, James Clerk Maxwell, a Scottish scientist, formulated a comprehensive set of equations—known as Maxwell’s equations—that explain how electric and magnetic fields interact. These equations are fundamental in our current understanding of electromagnetism.
In the 20th century, the advent of quantum mechanics brought about a deeper understanding of electric fields at a subatomic level. Studies by Albert Einstein and others showed that electric fields play a crucial role in the behavior of photons and electrons, paving the way for the development of modern electronics.
Recent research, for instance, has explored methods to reduce error rates in silicon qubits based on electron spins confined in quantum dot structures. This research is part of ongoing efforts to harness and manipulate electric fields, which continue to drive forward the boundaries of innovation in electronics and related fields.
