Module 1.1: Foundations of Electrostatics

Electric Charge

A fundamental intrinsic property of matter that governs how particles interact through electromagnetic forces.

Positive Charge

A type of electric charge carried by protons.

Negative Charge

A type of electric charge carried by electrons.

Coulomb (C)

The SI unit of electric charge.

Fundamental Charge (e)

The smallest isolated charge found in nature, approximately 1.60 x 10^-19 C.

Quantization of Charge

The principle that the total charge of an object must be an integer multiple of the elementary charge.

Law of Conservation of Charge

In an isolated system, the total charge remains constant; charge cannot be created or destroyed.

Conductors

Materials that allow charge carriers to move freely, such as metals like copper and gold.

Insulators

Materials where electrons are tightly bound to atoms and cannot move freely, like rubber or glass.

Charging by Friction

The process where electrons are transferred between two different insulators when rubbed together.

Charging by Conduction

The transfer of charge via direct physical contact between conductors.

Charging by Induction

A method of charging a conductor without physical contact, involving grounding.

Coulomb's Law

A law describing the electrostatic force between two point charges, given by the formula FE = k |q1 q_2| / r^2.

Coulomb's Constant (k)

A constant approximately equal to 8.99 x 10^9 N·m²/C².

Permittivity of Free Space (ε₀)

A constant approximately equal to 8.85 x 10^-12 C²/(N·m²), used in Coulomb's law.

Electrostatic Force

A vector force between charged objects; depends on both magnitude and direction.

Principle of Superposition

The net electric force on a charge is the vector sum of all forces from other charges.

Linear Charge Density (λ)

Charge per unit length, expressed as dq = λ dl.

Surface Charge Density (σ)

Charge per unit area, expressed as dq = σ dA.

Volume Charge Density (ρ)

Charge per unit volume, expressed as dq = ρ dV.

Shell Theorem

A uniformly charged spherical shell acts like a point charge only outside the shell.

Debunking a Common Mistake

Not decomposing forces into components before vector addition is a common error in electrostatics.

Unit Conversion

Remembering that 1 μC = 10^-6 C and 1 nC = 10^-9 C is crucial for accurate calculations.

Induction vs. Conduction

Induction creates opposite net charge to the source while conduction maintains the same net charge.

Polarity of Charges

Like charges repel each other, while opposite charges attract.

Magnitude of Electric Force

Calculated using Coulomb's Law, impacted by distance and magnitudes of the charges.