Understanding Electrostatics: Charge, Fields, and Lightning

Understanding Electrostatics

Electrostatics is the branch of physics that studies the phenomena produced by charges that do not vary or move.

History of Electrostatics

6th century BC: The Greeks discovered the electrical properties of amber. When rubbed, it could attract light objects.

18th century: Benjamin Franklin conducted experiments with different materials and observed that rubbed materials could either attract or repel each other.

Franklin's Theory of Electricity

• There are only two types of electricity: positive and negative.
• Electricity is a sort of fluid present in all objects and it can flow from one object to another by rubbing them.
• When there's an excess of electricity, objects have positive electricity, and when there's a lack of electricity, objects have negative electricity.
• Objects with different electricities attract each other, and objects with equal electricity repel.

Electric Charge

Electric charge is measured in Coulombs.

• Particles can have positive, negative, or no charge.
• Only negative charge is transferred by means of electron transfer. Electrons are the outermost particles of an atom and they can pass from one object to another.

Properties of Electric Charges

Charges of the same sign repel, while charges of different signs attract.

Electric Charge Conservation

In an isolated system, the overall electric charge does not vary.

Electric charge is not generated from nothing but only transferred from one object to another.

Importance of Electrical Phenomena

• On a large scale, electric forces are responsible for the physical states of many substances.
• The properties that we perceive from the objects that surround us (hardness, resistance, etc.) are the result of the electric forces between the molecules and the atoms that constitute them.
• Electric current is the most important application of electricity and it involves electrons that move thanks to an electric force.

Materials

• Conductors: They allow the flow of electrons. Example: metals
• Insulators: They don't allow the flow of electrons. Example: plastic, glass

Lightning

1. In a cloud, little water drops and ice crystals get charged when rubbed. The electrical charges separate.
2. The molecules of the ground align themselves with their positive part located on the ground surface.
3. Discharge of electrons due to the accumulation of charge.

Lightning Conductors

Pointed metallic objects that have the property of accumulating large densities of electric charge. They are used to attract lightning.

Coulomb's Law

Charged objects exert forces on each other.

Forces depend on:

• Charge: The force increases when the charges of the bodies increase.
• Distance: The force decreases when the distance increases.

Electric Field

A charge causes an alteration all over the space around it. This alteration is known as the electric field, and this field exerts a force on other charges.