Electrical Engineering Basics for Beginners: A Complete Guide to Voltage, Current, and Ohm's Law

 Introduction

Electrical engineering is a branch of engineering concerned with the study and application of electricity, electronics, and electromagnetism. The fundamentals of electrical engineering are essential for anyone wishing to understand or work in the electrical field, whether on a domestic, industrial, or high-tech scale.

In this lesson, we will discuss three basic concepts that form the foundation of electrical engineering: voltage, current, and Ohm's Law. These three concepts are crucial because they form the basis for designing, analyzing, and solving electrical problems.

1. What is Electricity?

Before discussing further, we must understand what electricity is. Electricity is the flow of electrical charge, usually in the form of electrons, moving through a conductor such as a copper wire. This flow occurs due to a potential difference (voltage) between two points.

Electrical energy is a primary source of modern life—used to power lights, electronic devices, electric motors, and even charge electric cars. To understand how electricity works, we must understand some basic units and concepts.

2. Electrical Voltage (Voltage)

a. Definition of Voltage

Electric voltage is the electrical potential difference between two points in a circuit. Voltage provides the "push" for electrons to flow in a conductor. Without voltage, there would be no electric current.

b. Units of Voltage

The unit of voltage is the volt (symbolized by the letter V). Voltage is often measured using a device called a voltmeter.

c. Voltage Sources

Some examples of voltage sources:

Battery: produces direct current (DC).

Generator: produces alternating current (AC).

Adapter: converts voltage from AC to DC.

d. Symbols and Notations

The common symbol for voltage in a circuit is the letter V, for example:

VAB indicates the voltage from point A to B.

3. Electric Current

a. Definition of Current

Electric current is the amount of electric charge flowing in a conductor per unit of time. Current occurs when electrons move from one point to another due to a voltage.

b. Units of Current

The unit of electric current is the Ampere (A). The instrument used to measure current is an ammeter. On a smaller scale, current can also be measured in milliamperes (mA), where 1 A = 1000 mA.

c. Types of Electric Current

Direct Current (DC): Electrons flow in one direction only, as in a battery.

Alternating Current (AC): The direction of electron flow changes, used in the PLN electricity network.

d. Notation and Symbols

The common symbol for current is the letter I, from the Latin word “intensitas”:

I : Q/t , where : 

I: current (Amperes)

Q: electric charge (Coulombs)

t: time (seconds)

4. Ohm's Law

a. Definition

Ohm's Law is a fundamental law in electricity that explains the relationship between voltage (V), current (I), and resistance (R). This law was discovered by Georg Simon Ohm, a German physicist in the 19th century.

b. Ohm's Law Formula

The basic formula for Ohm's law is:

Description:

V: Voltage in Volts (V)

I: Current in Amperes (A)

R: Resistance in Ohms (Ω)

c. Formula Application

From the formula above, we can derive two other formulas:

d. Case Example

For example, a lamp is connected to a 12-volt battery with a resistance of 6 ohms. The current flowing is:

The Importance of Ohm's Law

Ohm's Law helps us understand how electrical components work and allows us to design electrical systems safely and efficiently.

5. Electrical Resistance

a. Definition of Resistance

Electrical resistance is the opposition of a material to the flow of electric current. The greater the resistance, the more difficult it is for the current to flow.

b. Units of Resistance

The unit of resistance is the ohm (Ω).

c. Factors Affecting Resistance

• Material Type: Metals such as copper have low resistance.
• Conductor Length: The longer the cable, the greater the resistance.
• Cross-sectional Area: The thicker the cable, the lower the resistance.
• Temperature: Resistance typically increases with temperature.

a. Series Network

In a series circuit, all components are arranged sequentially in one line. The current flowing is the same in each component.

total voltage : V1​+V2​+...+Vn

b. Parallel Circuit

In a parallel circuit, components are connected side by side, each receiving the same voltage.

Total current: I1​+I2​+...+In

Total resistance : 

​c. Series-Parallel Combinations

In practice, many circuits consist of a combination of series and parallel connections. The calculation principle remains the same and is usually performed in stages.

7. Electrical Measuring Instruments

To study electricity, we need to know the following essential measuring instruments:

• Voltmeter: Measures voltage.
• Ammeter: Measures current.
• Ohmmeter: Measures resistance.
• Multimeter: A combination of all three, a versatile tool that every technician must have.

​8. Safety in Electrical Engineering

• Safety is crucial when working with electricity. Here are some basic tips:
• Always turn off the power source before working.
• Use protective equipment such as insulating gloves and rubber boots.
• Do not touch exposed wires.
• Ensure equipment and installations comply with standards (e.g., SNI or IEC).
• Use fuses or automatic circuit breakers (MCBs) to prevent short circuits.

9. Application in Daily Life

• Knowledge of voltage, current, and Ohm's law is very useful in everyday life, for example:
• Determining the appropriate type of battery for a particular device.
• Fixing a household light that won't work.
• Calculating the power requirements of electronic devices to ensure they don't exceed the home's electrical capacity.
• Designing a solar panel or inverter system.

Conclusion

Understanding the fundamentals of electrical engineering, such as voltage, current, and Ohm's Law, is crucial as a first step in exploring the world of electricity. These concepts are the foundation of almost all electrical and electronic technology, from household appliances to complex industrial systems.

For beginners, start by understanding these basic theories and move on to simple practical exercises such as building a light circuit, measuring current with a multimeter, and calculating power requirements. With a solid understanding, you can advance further in the world of electrical engineering—toward electronic circuit design, automation, or even robotics.