So, we’ve all heard of the popular saying, “like charges repel and unlike charges attract, but where do we get this from? Electrostatics is where. Electrostatics is a division of physics that deals with slow-moving or static electrical charges aka static electricity.
There are many instances of electrostatics that can be observed in our daily lives. One very common occurrence is when a balloon is rubbed on hair causing it to be electrically charged. And so, when it is put alongside another balloon, they attract to one another. After combing your hair, have you ever noticed that the tip of the comb tends to attract small particles such as pieces of paper? Well, this is another instance of Electrostatics.
Electric charge
Electric Charge is one of the fundamental properties of matter that allows it to experience force in conditions of either an electric or magnetic field.
There are two primary types of Electric charges. A positive and a negative charge. A positive charge is denoted by a (+) symbol and is linked to a proton. A negative charge on the other hand is denoted by a (-) symbol and is linked to an electron. A proton and electron are two of three subatomic particles that inhabit an atom, the other is a neutron. Now for an atom to be either positively or negatively charged, it must have a greater number of protons than electrons for a positively charged atom or greater number of electrons than protons for a negatively charge atom. When an atom has an equal number of both proton and electron, it is called a neutral atom.
When two atoms of like charges, let’s say positive and positive meet, they repel one another. But, when two atoms of opposite charges meet, they attract to one another. This basic principle is the foundation upon which many complex concepts are derived from in physics.
Methods of charging
Alright great! So, we know what an electric charge is, but how does one go about attaining it? There are three ways in which charge can be attained:
- Friction
- Conduction
- Induction
Charging by friction
When two neutral objects are brought together and rubbed off one another, a sub atomical transfer happens. One of the objects will gain an electron, causing it to be negatively charged and the other object losing an electron will have an excess number of protons, causing it to be positively charged.
Charging by conduction
Charging via conduction is a slightly different process. For one, it requires an object that already has a charge, the more excess charge the better. When the two objects are put in contact, the one with charge transfers its charge to the neutral object. Causing both to be charged.
Charging by Induction
Charging by induction occurs when a neutral object is brought in close proximity to a charged object (note: the two objects are not touching). Depending on the type of charge on the charged object, it will cause the neutral object to gain the opposite of that charge. This causes the two objects to attract to one another.
Coulomb’s law
Electrostatics can be depicted by Coulomb’s Law which measures the amount of Force present between two static electrically charged particles. According to this law, the magnitude of the attractive or repulsive electrostatic force between two charged particles(F) is directly proportional to the product of their charges(q) and inversely proportional to the distance between them(r) squared. The formula below showcases Coulomb’s Law:
$$
F=k_e \frac{q_1 q_2}{r^2}
$$
- F = Electric force.
- ke = Coulomb constant.
- q1 & q2 = Charge of particles.
- r = Distance between the two particles.
The coulomb constant denoted by (k / ke / K) is a proportional constant that helps us find what the strength of interaction between two charged particles is due to their electric charges. Coulomb’s constant is often denoted by the formula:
$$
k_e=\frac{1}{4 \pi \varepsilon_0}
$$
- ke = Coulomb’s constant = 9 x 109 N.m2.C-2
- E0 = The vacuum permittivity = 8.854 x10-12 F.m-2
Electric field
An electric field (often referred to as electric field intensity) can be seen as an invisible space surrounding an electrically charged object. Now when an object is placed in this field, it experiences either an attractive or repulsive force. The electric field tells us how strong the force is for different points around the charged object. It can also be defined as the measure of electric force per unit charge. The formula for Electric field is given as:
$$
E=\frac{F}{Q}
$$
- E = Electric field.
- F = Electric force.
- Q = The charge.
Electric potential
The electric potential energy is the energy that is required to move a charge against the force of an electric field. This means that when we have an attractive force, the amount of energy that is needed to move a charge away from that attractive force is the electric potential energy but when we have a repulsive force, it is the amount of energy needed to move a charge towards the repulsive force. If an electric field is defined as the measure of electric force per unit charge then it can be said that electric potential is just the electric potential energy per unit charge. Electric potential is measured in volts (V) where 1 volt is equivalent to 1 joule of electric potential energy per coulomb of charge.
Electric Flux
Electric Flux is the measure of electric field lines that penetrate a given surface. The electric field lines that are directed out of a closed surface experience negative electric flux and the ones directed inwards through a closed surface are thought of as positive electric flux. The formula for finding the electric flux is written below:
$$
\emptyset_E=E \cdot S=E S \cos \theta
$$
- E = Electric field.
- S = The area of the surface.
- E = Magnitude.
- θ = The angle between the electric field lines and the normal.
- ∅ = The flux of electric field through a closed cylindrical surface.
Now the mathematical association between the electric flux and an enclosed charge is known as Gauss’s law. Gauss’s law . Electric flux measures the flow of electric field through any given surface. Gauss’s law is specific to only enclosed surfaces and as such it is one of the fundamental laws of electromagnetism. The formula for Gauss’s law is writing as:
$$
\emptyset_E=\frac{Q}{\varepsilon_0}
$$
- ∅E = Electric flux through a closed surface.
- Q = Total charge enclosed.
- E0 = Electric constant.
All the concepts that are listed above are all interconnected to one another, many times you can’t get one without other. It is important to understand each one of these concepts separately and how it relates to another. This will provide you with a broad and comprehensive understanding of the electrostatic interactions that go on in any given system.
