Understanding Electricity: Electrons, Circuits, and Ohm's Law

What Is an Electron?

An electron is a subatomic fermionic elementary particle.

Relationship With Electricity

Electrons carry a negative charge; their movement through a material conducts electricity.

What Is Electric Current?

Electric current is the flow of charge per unit of time (per second) traveling through a material.

Types of Current

• Direct Current: Electrons flow in the same direction.
• Alternating Current: Electrons change direction 50 times per second.

Ohm's Law

Ohm's Law defines the relationship between voltage, current, and resistance:

• R (Resistance): Measured in ohms (Ω). Formula: R = V / I
• I (Intensity/Current): Measured in amperes (A). Formula: I = V / R
• V (Voltage): Measured in volts (V). Formula: V = R × I

The Electric Circuit

An electric circuit is the path along which electrons travel. It consists of the following elements:

• A wire (conductor).
• A receiver (e.g., bulb, buzzer, or motor).
• A generator.

Elements of an Electric Circuit

1. Generators: Batteries and cells.
2. Receivers: Relays, light bulbs, motors, and buzzers.
3. Control Elements: Switches and buttons.
4. Protection Elements: Fuses and resistors.
5. Measuring Instruments: Ammeters and voltmeters.

Electrical Quantities

1. Voltage: Also known as potential difference.
2. Intensity: Measured in Amps; the amount of charge passing through a conductor in one second (1 A = 1 coulomb/second).
3. Resistance: The opposition offered by a material to the flow of electric current, measured in ohms.

Circuit Configurations

Series Circuit

Components are connected so the output of one is the input of the next. The current is the same in all elements, and the total voltage is the sum of the voltage in each element (R_total = R₁ + R₂ + R₃...).

Parallel Circuit

Components are placed so all have the same input and output. The potential difference across different elements is the same (V_total = V₁ = V₂ = V₃...; I_total = I₁ + I₂ + I₃...).

Joint Circuit

A combination of series and parallel circuits.

Electric Power and Energy

Electric Power (P): The ability of a receiver to transform energy in a given time (P = V × I).

Electrical Energy (E): Energy consumed can be expressed in terms of power (kWh). 1 kWh = 3,600,000 Joules (3,600 kJ). The Joule is also measured in calories.

To calculate electrical energy: E = P × t

• E: Measured in Joules.
• P: Measured in Watts (W) or kilowatts (kW).
• t: Measured in hours.