Fundamentals of Electricity and Circuits

Methods of Electrification

• Electrification by Friction

  This process involves the transfer of electrons, where one material loses electrons and another gains them.

• Electrification by Induction

  In this method, no electron transfer occurs between objects. Instead, there is a redistribution of existing electric charges within the body.

• Electrification by Contact

  When a negatively charged object touches a neutral body, negative charge is transferred from the charged body to the neutral one.

Lightning: Natural Electrical Discharges

Clouds become electrically charged by friction with air due to their motion. The top of a cloud often becomes positively charged, while the bottom accumulates negative charges. This charge separation, along with the Earth's surface, creates a significant potential difference. When these charges accumulate to a certain magnitude, they can result in strong electrical discharges:

• Between different points within the cloud with opposite charges.
• Between different clouds.
• Between a cloud and the Earth.

These powerful electrical discharges are known as lightning.

Electric Current and Ohm's Law

• Electric Current

  Electric current is the flow of electric charge, typically electrons. It flows through conductors, such as cables, when there is a voltage difference (potential difference) between the ends of the conductor.

• Batteries

  Batteries release energy through internal chemical reactions, converting chemical energy into electrical energy.

• Ohm's Law

  Ohm's Law states that the electric current (I) flowing through a conductor is directly proportional to the potential difference (V) across its ends and inversely proportional to its resistance (R). This relationship is commonly expressed as V = IR.

Simple Circuit Components

Simple electrical circuits typically consist of:

• Power Source: Provides the voltage (e.g., battery).
• Conductors: Materials that allow current to flow (e.g., wires).
• Resistors: Components that oppose the flow of current.

Series Circuits

Series circuits are governed by the following rules:

• Equivalent Resistance: The total (equivalent) resistance is equal to the sum of all individual resistances (R_total = R₁ + R₂ + ...).
• Current Flow: The electric current has only one path to flow through the circuit, meaning the current is the same through all components.
• Voltage Distribution: The sum of the potential differences (voltage drops) across each resistor is equal to the total voltage supplied by the source.

Parallel Circuits

The rules for parallel circuits are:

• Current Division: The total circuit current splits among the parallel branches. The sum of the currents flowing through each resistor is equal to the total circuit current (I_total = I₁ + I₂ + ...).
• Voltage Across Components: The potential difference (voltage) across all resistors in parallel is the same and is equal to the voltage supplied by the source.
• Equivalent Resistance: The reciprocal of the total equivalent resistance is equal to the sum of the reciprocals of individual resistances (1/R_total = 1/R₁ + 1/R₂ + ...).

Electrical Conductors and Control

Electrical conductors are the components that carry electric current, and devices like switches are used to control (turn on/off) the current flow within a circuit.