Basic Electrical Engineering Formulas PDF: Important Formulas, Laws and Network Theorems

Search Description: Download and learn basic electrical engineering formulas including Ohm's law, power formulas, KCL, KVL, Thevenin theorem, Norton theorem, AC formulas, capacitor, magnetism and three-phase formulas.

Introduction

Basic electrical engineering formulas are very important for students, electricians, technicians and engineers. These formulas help in solving circuits, calculating power, finding resistance, understanding AC and DC systems, analyzing capacitors, applying network theorems and studying magnetic circuits.

This post is prepared for educational purposes. It gives a clean overview of important topics included in the Basic Formula of Electrical Engineering PDF. Students can use this article for quick revision before exams, interviews, practical work and competitive preparation.

What is Included in This Electrical Formula Notes?

The notes cover many important formulas from basic electricity, electrical network theory, electrostatics, AC fundamentals, magnetism, electromagnetic induction, three-phase systems and two-port networks.

Table of Contents

• Basic of electricity
• Electrical network theorems
• Electrostatics formulas
• AC circuit fundamentals
• Magnetization and magnetic circuit
• Electromagnetic induction
• Three-phase system formulas
• Two-port network parameters
• Embedded PDF notes
• Frequently asked questions

1. Basic of Electricity

The basics of electricity form the foundation of electrical engineering. Every student should clearly understand voltage, current, resistance, power, energy and circuit laws.

• Effect of temperature on resistance
• Series and parallel connection of resistance
• Ohm’s law
• Power calculation in DC circuits
• Power calculation in AC circuits
• Current division rule
• Voltage division rule
• Direction of EMF sources
• Thevenin’s theorem
• Norton’s theorem

Important Basic Formulas

Topic	Formula
Ohm’s Law	V = I × R
Power in DC	P = V × I = I²R = V²/R
Energy	Energy = Power × Time
Series Resistance	R = R1 + R2 + R3 + ...
Parallel Resistance	1/R = 1/R1 + 1/R2 + 1/R3 + ...
Temperature Effect	Rt = R0(1 + αt)

2. Basic Electrical Network Theorems

Network theorems are used to simplify complex electrical circuits. These theorems are very useful in circuit analysis, electronics, power systems and electrical machines.

• Kirchhoff’s Current Law
• Kirchhoff’s Voltage Law
• Source conversion
• Maximum power transfer theorem
• Superposition theorem
• Reciprocity theorem
• Millman’s theorem
• Thevenin’s theorem
• Norton’s theorem

Important Network Theorem Notes

• KCL: The algebraic sum of currents entering and leaving a node is zero.
• KVL: The algebraic sum of voltages around a closed loop is zero.
• Thevenin’s theorem: A complex network can be replaced by a voltage source and series resistance.
• Norton’s theorem: A complex network can be replaced by a current source and parallel resistance.
• Maximum power transfer: Maximum power is transferred when load resistance equals source/internal resistance in DC circuits.

3. Electrostatics

Electrostatics deals with electric charges at rest. It is important for understanding capacitors, electric fields, dielectric materials and high-voltage systems.

• Coulomb’s law
• Electric field intensity
• Electric flux density or charge density
• Electric potential
• Capacitor
• Series and parallel combination of capacitors
• Charging of a capacitor
• Discharging of a capacitor

Important Electrostatic Formulas

Topic	Formula
Coulomb’s Law	F = kQ1Q2/r²
Electric Field	E = F/Q
Capacitance	C = Q/V
Energy Stored in Capacitor	W = 1/2 CV²
Capacitors in Parallel	C = C1 + C2 + C3 + ...
Capacitors in Series	1/C = 1/C1 + 1/C2 + 1/C3 + ...

4. Fundamentals of AC

AC circuits are widely used in power systems, homes and industries. Understanding RMS value, peak value, frequency, impedance, reactance and power factor is very important.

• Instantaneous value
• Average value
• RMS value
• Peak value
• Form factor
• Peak factor
• Impedance
• Inductive reactance
• Capacitive reactance
• Power factor

Important AC Formulas

Quantity	Formula
RMS Value	Vrms = Vm/√2
Frequency	f = 1/T
Inductive Reactance	XL = 2πfL
Capacitive Reactance	XC = 1/(2πfC)
AC Power	P = VI cosφ
Apparent Power	S = VI

5. Magnetization and Magnetic Circuit

Magnetic circuits are important in transformers, motors, generators, relays and inductors. These formulas help in understanding flux, reluctance, magnetomotive force and magnetic field strength.

• Magnetic flux
• Flux density
• Magnetic field intensity
• Magnetomotive force
• Reluctance
• Permeability
• Hysteresis loss
• Eddy current loss

6. Electromagnetic Induction

Electromagnetic induction is the basic principle behind transformers, generators and many electrical machines.

• Faraday’s law of electromagnetic induction
• Lenz’s law
• Dynamically induced EMF
• Statically induced EMF
• Self-inductance
• Mutual inductance

Important Induction Formulas

Topic	Formula
Induced EMF	e = -N dΦ/dt
Inductance	L = NΦ/I
Energy Stored in Inductor	W = 1/2 LI²

7. Three-Phase System

Three-phase systems are used for power generation, transmission, distribution and industrial motors. They are more efficient and economical than single-phase systems for large power applications.

• Star connection
• Delta connection
• Line voltage and phase voltage
• Line current and phase current
• Three-phase power
• Power factor

Important Three-Phase Formulas

Quantity	Formula
Three-Phase Power	P = √3 VL IL cosφ
Reactive Power	Q = √3 VL IL sinφ
Apparent Power	S = √3 VL IL
Star Connection	VL = √3 Vph, IL = Iph
Delta Connection	VL = Vph, IL = √3 Iph

8. Two-Port Network

Two-port networks are useful in circuit theory, electronics, communication networks and filter design.

• Z-parameters
• Y-parameters
• T-parameters
• Hybrid parameters
• ABCD parameters

Download / View Basic Formula of Electrical Engineering PDF

You can view the electrical engineering formula PDF below. If it does not open properly, open it in a new browser tab or download it from Google Drive.

Who Should Read These Formula Notes?

• Electrical engineering students
• Diploma students
• ITI electrician students
• Technicians and electricians
• Competitive exam aspirants
• Interview preparation students
• Beginners learning electrical circuits

Frequently Asked Questions

Which formula is most important in electrical engineering?

Ohm’s law, V = IR, is one of the most important formulas because it connects voltage, current and resistance.

What is the formula for electrical power?

In DC circuits, power is P = VI. In single-phase AC circuits, real power is P = VI cosφ. In three-phase circuits, power is P = √3 VL IL cosφ.

Why are network theorems important?

Network theorems simplify complex circuits and make circuit analysis easier.

What is the difference between AC and DC formulas?

DC formulas usually involve only voltage, current and resistance, while AC formulas also include frequency, reactance, impedance and power factor.

Are these formulas useful for exams?

Yes, these formulas are useful for diploma exams, engineering exams, ITI exams, competitive exams and interviews.

Conclusion

Basic electrical engineering formulas are the foundation of circuit analysis, electrical machines, power systems and electronics. Students should revise these formulas regularly and practice numerical problems to understand them clearly.

If you are a beginner, start with Ohm’s law, power formulas, series-parallel circuits, KCL, KVL and capacitor formulas. After that, move toward AC circuits, magnetic circuits, electromagnetic induction and three-phase systems.