Electron Theory

Basic Principles of Electricity

  • Understanding the basics is crucial for working with electricity, magnetism, and electrochemical reactions.

  • Knowledge of atomic composition is necessary for safety in the industry.

Atomic Theory (Electron Theory)

  • Atoms are tiny particles, consisting of:

    • Nucleus: Contains protons (positive) and neutrons (neutral).

    • Electrons: Negatively charged, orbiting the nucleus.

  • Key terms:

    • Atomic Theory: Study of atoms and electrons.

    • Electron: Negatively charged component of an atom.

Structure of Atoms

  • Atoms consist of different numbers of electrons, equal numbers of protons and electrons make the atom electrically neutral.

  • Atoms in solids and liquids are more tightly bound than in gases.

  • Different materials have different atomic structures (e.g., copper conducts electricity).

Electron Shells

  • Electrons orbit in paths called shells, with:

    • First shell: Holds up to 2 electrons.

    • Second shell: Holds up to 8 electrons.

  • Valence Electrons: Electrons in the outermost shell, important in chemical bonding and electrical properties.

Electrical Conductivity

  • Measures a material's ability to conduct electric current.

  • High conductivity materials allow easy current flow, low conductivity materials resist it.

  • Influencing factors:

    • Temperature

    • Structure

    • Composition

    • Purity

  • Free electrons are crucial for conductivity and can move in response to electric fields.

Classification of Materials

  • Based on conductivity:

    • Conductors: Easily conduct electricity.

    • Semiconductors: Intermediate conductivity.

    • Insulators: Resist current flow.

Flow of Electrons (Electric Current)

  • Current is defined by the drift of electrons from the negative to positive terminal when a circuit is closed.

  • Closed Circuit: Complete circuit allowing current flow.

  • Open Circuit: Circuit where current flow ceases.

Direction of Current Flow

  • Conventional current flows from positive to negative (historical perspective).

  • Actual electron flow is from negative to positive.

  • Direct Current (DC): Current flows in one direction.

Measurement of Current

  • Current is measured in amperes (A), related to charge in coulombs (C).

  • 1 coulomb = 6.24 × 1018 electrons.

  • 1 ampere = 1 coulomb per second.

  • Formula: Q = It (Where Q = charge, I = current, t = time).