Basics of Electrical Engineering, First year, SPPU

Current voltage resistance Ohms law KCL KVL power DC AC current AC Circuit Transformer Induction Motor

Created byRupendra K Pathak

Last updated 5/2025

Hindi

What you'll learn

This course is for FIRST YEAR student of Savitribai Phule University Pune (SPPU)
This Course Basic of Electrical Engineering(BEE) is revised as per new syllabus 2024
Units covered are Elementary Concept and DC, Electromagnetism, Fundamental of AC, AC circuit, Transformer & Induction Motor
Student can learn all concepts in easy way and can obtain full marks in semester exam

Course content

5 sections • 63 lectures • 27h 8m total length

Basics of Charge31:40
Electric charge is a fundamental property of matter that causes it to experience a force when placed in an electromagnetic field. It's the basis for electricity and electromagnetic interactions.
There are two types of electric charge:
Positive charge (e.g. carried by protons)
Negative charge (e.g. carried by electrons)
Like charges repel, and opposite charges attract.
Units and Measurement
SI Unit: Coulomb (C)
Elementary charge (e):
The smallest unit of charge found in nature.
e≈1.602×10−19 C
Key Concepts
Conservation of charge: Electric charge is neither created nor destroyed.
Quantization of charge: All observable charges are integer multiples of the elementary charge.
Conduction and Insulation: Materials that allow charge to flow easily are called conductors (e.g. copper); those that don’t are insulators (e.g. rubber).
EMF and Potential Difference25:31
EMF (Electromotive Force)
Definition:
EMF is the energy provided by a power source (like a battery or generator) per unit charge to move charges through a complete circuit.
Symbol: E
Unit: Volt (V)
Formula:
E=Work done/Charge
Example: A 12V battery has an EMF of 12 volts, meaning it gives 12 joules of energy per coulomb of charge.
Important: EMF is not a force, despite the name. It's a measure of energy per charge.
Potential Difference (Voltage)
Definition:
Potential difference is the difference in electric potential between two points in a circuit. It tells you how much energy is used (or lost) as a charge moves between those two points.
Symbol: V
Unit: Volt (V)
Formula:
V=W/Q
Example: If a resistor drops 6V across it, it means 6 joules of energy are used per coulomb passing through.
Basics of Current27:02
What Is Electric Current?
Electric current is the flow of electric charge through a conductor (like a wire).
Symbol: I
Unit: Ampere (A)
? Definition
I=Q/t
Where:
I= current (in amperes)
Q = charge (in coulombs)
t = time (in seconds)
In words: Current is the amount of charge that flows past a point per second.
Types of Current
Direct Current (DC):
Flows in one direction
Example: batteries
Alternating Current (AC):
Reverses direction periodically
Example: household electricity
What Causes Current?
A potential difference (voltage) across a conductor.
Electrons move from the negative to the positive terminal, but by convention, current is considered to flow from positive to negative.
Key Points
1 Ampere = 1 Coulomb/second
Metals are good conductors because they have free electrons
In circuits, current is the same at every point in a series circuit, but divides in parallel circuits.
Example
If 10 coulombs of charge pass through a wire in 2 seconds:
I=10/2=5A
Resistance23:06
Resistance is the opposition that a material offers to the flow of electric current.
Symbol: R
Unit: Ohm (Ω)
It determines how much current will flow for a given voltage.
Ohms Law19:57
Ohm's Law is a fundamental principle in electrical circuits that relates voltage (V), current (I), and resistance (R). Here's the core formula:
V=I×R
Explanation:
V = Voltage (in Volts, V): The potential difference between two points in a circuit.
I = Current (in Amperes, A): The flow of electric charge.
R = Resistance (in Ohms, Ω): The opposition to the flow of electric current.
Rearranged Forms of Ohm’s Law:
To find current (I):
I=V/R
To find resistance (R):
R=V/I
Key Points:
Direct Proportionality: Current is directly proportional to voltage and inversely proportional to resistance.
If voltage increases, current increases (if resistance stays the same).
If resistance increases, current decreases (if voltage stays the same).
Linear Relationship: Ohm's Law assumes that the material's resistance remains constant as voltage changes (this is true for ohmic materials like metals).
Power system31:57
A power system is a network of electrical components that generates, transmits, and distributes electrical power. It is designed to supply electrical energy to consumers, from power plants to homes and industries. Here's an overview of the key components and terms related to power systems:
Power Generation:
Power Plant: A facility that generates electricity using various energy sources (fossil fuels, nuclear, solar, wind, hydro, etc.).
Types of Power Plants:
Thermal Power Plants (coal, natural gas, oil)
Hydroelectric Power Plants
Nuclear Power Plants
Renewable Power Plants (solar, wind, biomass)
Transmission:
High-Voltage Transmission Lines: Carry electricity from power plants to substations over long distances at high voltage to minimize energy loss.
Transmission Substation: A facility where voltage is stepped up or down using transformers to transmit power over long distances.
Transmission Voltage: Typically ranges from 110 kV to 765 kV (kilo-volts).
Distribution:
Distribution Lines: Carry electricity from substations to homes, businesses, and industries at lower voltage (typically from 110 V to 480 V).
Distribution Substations: Step down voltage from high transmission levels to usable levels for consumers.
Protection and Control:
Circuit Breakers: Devices used to protect electrical circuits from damage due to overcurrent or faults by interrupting the flow of electricity.
Relays: Used to detect abnormal conditions and activate circuit breakers to protect the system.
Fuses: Provide protection by melting when excessive current flows through them.
SCADA Systems: Supervisory Control and Data Acquisition systems that monitor and control the power grid remotely.
Transformers:
Step-up Transformers: Increase voltage for long-distance transmission.
Step-down Transformers: Decrease voltage for safe use at homes and businesses.
Types Of Network30:28
Linear vs. Non-linear:
In a linear network, the relationship between voltage and current is constant and predictable, while in a non-linear network, this relationship can change with varying conditions like voltage or current.
Bilateral vs. Unilateral:
A bilateral network allows current to flow equally in either direction, while a unilateral network exhibits different behavior in different directions.
Active vs. Passive:
Active networks contain sources of energy (like voltage or current sources) that can generate and add energy to the circuit, while passive networks consist only of elements like resistors, capacitors, and inductors that consume energy.
Lumped vs. Distributed:
Lumped networks assume that elements (like resistance, inductance, and capacitance) are concentrated in small, discrete locations, while distributed networks consider these elements as spread out over a larger area or distance
Connection of resistances: Series & Parallel34:00
. Series Connection of Resistors
In a series circuit, the resistors are connected one after another, forming a single path for the current to flow.
Characteristics:
The same current flows through each resistor.
The total resistance is the sum of all individual resistances.
Formula for Total Resistance (Rₜ):
Rtotal=R1+R2+R3+⋯+Rn
Where R1,R2,R3,…,Rn are the individual resistances.
E
2. Parallel Connection of Resistors
In a parallel circuit, the resistors are connected across the same two points, providing multiple paths for the current to flow.
Characteristics:
The voltage across each resistor is the same.
The total resistance is always less than the smallest individual resistor.
Formula for Total Resistance (Rₜ):
1/Rtotal=1/R1+1/R2+1/R3+⋯+1/Rn\
Where R1,R2,R3,…,Rn are the individual resistances.
Star delta connection of resistances35:31
KCL KVL42:07
KCL (Kirchhoff's Current Law):
The total current entering a junction is equal to the total current leaving the junction.
KVL (Kirchhoff's Voltage Law):
The sum of all voltages around a closed loop is zero.
Power20:49
Electrical power is given by the product of voltage (V) and current (I):
P=V×IP = V \times IP=V×I
Where:
P = Power (in Watts, W)
V = Voltage (in Volts, V)
I = Current (in Amperes, A)
Key Points:
Unit of Power: The unit of power is the Watt (W). One watt is equal to one joule of energy used per second.
Power in AC Circuits: In alternating current (AC) circuits, power can be expressed as:
P=Vrms×Irms
Super position theorem21:39
e Superposition Theorem states that:
In a linear circuit with multiple independent sources, the total response (voltage or current) in any component is the algebraic sum of the responses caused by each independent source acting alone, while all other independent sources are turned off.
Steps to Apply Superposition Theorem:
Identify all independent sources in the circuit.
Turn off all but one source:
To turn off a voltage source, replace it with a short circuit (i.e., zero voltage).
To turn off a current source, replace it with an open circuit (i.e., zero current).
Analyze the circuit with only one source active.
Repeat steps 2 and 3 for each independent source.
Sum all the individual effects from each source to get the total response.
Numerical on KCL KVL46:51

Magnetic Field Line21:47
Magnetic field lines are imaginary lines used to represent the direction and strength of a magnetic field. They show the path that a north magnetic pole would follow if placed in the field.
In simple terms:
Magnetic field lines are visual representations that show how magnetic force is distributed around a magnet.
Key Points to Include in a Definition:
They indicate the direction of the magnetic field (from North to South outside the magnet).
The closeness of the lines shows the strength of the magnetic field.
They form closed loops, continuing through the magnet from South to North internally.
Magnetic Flux Density10:23
Magnetic flux density (also called magnetic field strength) is defined as the amount of magnetic flux passing per unit area perpendicular to the direction of the magnetic field.
Formal Definition:
Magnetic flux density is the magnetic flux per unit area.
Magnetic Field Strength18:42
Definition of Magnetic Field Strength:
Magnetic field strength (also called magnetic field intensity) is a measure of the magnetizing force that produces a magnetic field in a material or space. It represents how strong the magnetic field is at a given point independent of the material’s response.
Formal Definition:
Magnetic field strength is the amount of magnetizing force per unit length.
It is denoted by H and measured in amperes per meter .
MMF19:18
Magnetomotive force (MMF) is the driving force that creates a magnetic field in a magnetic circuit, similar to how electromotive force (EMF) drives current in an electric circuit.
Formal Definition:
MMF is the force that establishes magnetic flux in a magnetic circuit.
It is denoted by F or sometimes just MMF, and its unit is the ampere-turn (At).
Formula:
F=N⋅I
Where:
F = magnetomotive force (in ampere-turns)
N = number of turns in the coil
I = current through the coil (in amperes)
? Analogy with Electrical Circuits:
MMF (magnetomotive force) is like voltage (EMF) in electrical circuits.
Magnetic flux is like electric current.
Reluctance (resistance to magnetic flux) is like resistance in an electric circuit.
Reluctance9:01
Reluctance is the property of a material or magnetic circuit that opposes the creation of magnetic flux, similar to how electrical resistance opposes electric current.
Formal Definition:
Reluctance is the opposition that a magnetic circuit offers to the passage of magnetic flux.
It is denoted by R and measured in ampere-turns per weber (At/Wb).
Formula:
R=l/μA
Where:
R = reluctance (At/Wb)
l = length of the magnetic path (in meters)
μ = permeability of the material (in henry per meter, H/m)
A = cross-sectional area of the path (in square meters, m²)
Series magnetic Circuit15:27
A series magnetic circuit is a type of magnetic circuit in which all magnetic elements (like different parts of an iron core or air gaps) are connected one after another, so the same magnetic flux flows through each part — just like electric current is the same in a series electrical circuit.
Magnetic circuit Vs Electric circuit18:01
Magnetic Circuit vs Electrical Circuit (Bullet Points)
Flow Quantity:
Magnetic Circuit: Magnetic flux (Φ)
Electrical Circuit: Electric current (I)
Driving Force:
Magnetic Circuit: Magnetomotive force (MMF), measured in ampere-turns (At)
Electrical Circuit: Electromotive force (EMF or Voltage), measured in volts (V)
Opposition to Flow:
Magnetic Circuit: Reluctance (?), measured in At/Wb
Electrical Circuit: Resistance (R), measured in ohms (Ω)
Material Used:
Magnetic Circuit: Magnetic materials (e.g., iron, steel)
Electrical Circuit: Conductive materials (e.g., copper, aluminum)
Governing Law:
Magnetic Circuit: F=Φ×R
Electrical Circuit: V=I×R
Energy Losses:
Magnetic Circuit: Hysteresis and eddy current losses
Electrical Circuit: I²R (resistive) losses
Path Nature:
Magnetic Circuit: Always a closed loop (magnetic lines of force are continuous)
Electrical Circuit: Must be closed for current to flow
Field Type:
Magnetic Circuit: Involves an invisible magnetic field
Electrical Circuit: Involves physical movement of electrons
Unit of Flow:
Magnetic Circuit: Weber (Wb) for flux
Electrical Circuit: Ampere (A) for current
Faraday Law19:49
Faraday's Law of Induction is one of the fundamental principles of electromagnetism. It describes how a changing magnetic field can induce an electrical current in a conductor. This is the basic principle behind devices like electric generators and transformers.
Statement of Faraday's Law:
The magnitude of the induced electromotive force (EMF) in a closed loop is directly proportional to the rate of change of magnetic flux through the loop.
Flaming and Lenz Law17:48
. Fleming's Right-Hand Rule:
Fleming’s Right-Hand Rule is used to determine the direction of induced current in a conductor moving through a magnetic field or in a generator setup.
Statement of Fleming's Right-Hand Rule:
If the thumb, forefinger, and middle finger of your right hand are arranged mutually perpendicular to each other:
Thumb represents the direction of motion of the conductor.
Forefinger represents the direction of the magnetic field.
Middle finger gives the direction of the induced current in the conductor.
How It Works:
In the case of a moving conductor (like in a generator), the magnetic field and motion of the conductor cause an electromotive force (EMF) or induced current. Fleming’s Right-Hand Rule helps find the direction of that current.
2. Lenz's Law:
Lenz's Law explains the direction of the induced current (EMF) and is a consequence of the conservation of energy. It states that the direction of the induced current will always be such that it opposes the change in magnetic flux that caused it.
Statement of Lenz's Law:
The induced current (or EMF) will always flow in a direction that opposes the change in magnetic flux through the circuit.
Mathematical Formulation (Faraday-Lenz Law):
E=−dΦ/dt
Where:
E is the induced electromotive force (EMF).
dΦ/dt is the rate of change of the magnetic flux.
The negative sign indicates that the induced EMF opposes the change in magnetic flux.
Types of EMF21:56
Induced EMF: Produced by a changing magnetic field. Example: Electric generators and transformers.
Contact EMF: Generated by electrochemical reactions between two different materials or electrodes. Example: Batteries and galvanic cells.
Thermal EMF (Seebeck Effect): Created by a temperature difference between two dissimilar conductors. Example: Thermocouples.
Photovoltaic EMF: Caused by light striking a material, knocking electrons loose. Example: Solar cells.
Chemical EMF: Arises from differences in the concentration of ions in an electrolyte. Example: Electrolysis.
Mutual EMF: Induced in a coil by a changing magnetic field from another nearby coil. Example: Transformers.
Self inductance26:54
Mutual Inductance24:15
Energy energy density23:29
PYQ 201958:05
PYQ202245:50

AC Basics33:38
Alternating Nature:
The current and voltage change direction and value continuously.
In most countries, AC changes direction 50 or 60 times per second (i.e., 50 Hz or 60 Hz).
Waveform:
The most common AC waveform is the sine wave.
Other forms include square wave and triangular wave.
Time period, frequency, angular frequency, amplitude16:52
Key Concepts of AC:
Alternating Nature:
The current and voltage change direction and value continuously.
In most countries, AC changes direction 50 or 60 times per second (i.e., 50 Hz or 60 Hz).
Waveform:
The most common AC waveform is the sine wave.
Other forms include square wave and triangular wave.
Cycle and Frequency:
Cycle: One complete oscillation of the waveform.
Frequency (f): Number of cycles per second, measured in Hertz (Hz).
Time Period (T):
Time taken to complete one cycle:
Amplitude (Peak Value):
The maximum value of current or voltage.
RMS (Root Mean Square) Value:
The effective value of AC, which gives the same heating effect as DC.
Average Value:
The average of all instantaneous values over a half-cycle of the waveform
RMS and Average Value28:23
RMS Value (Root Mean Square Value)
Definition:
The RMS value of an alternating current (or voltage) is the equivalent steady (DC) value that would produce the same amount of heat in a resistor as the AC does over one complete cycle.

Use:
It is the most commonly used value in AC analysis.
Multimeters measure RMS values by default.
2. Average Value
Definition:
The average value of an alternating quantity is the average of all instantaneous values over one half-cycle of the waveform (because over a full cycle, the average of a pure sine wave is zero).

Use:
Used mainly in rectifier circuits and for measuring unidirectional current.
Not suitable for power calculation in AC circuits.
Form Factor and Peak Factor29:14
Form Factor
Definition:
The form factor is the ratio of the RMS value to the average value of an alternating current or voltage waveform.
Form Factor=VRMS/VAverage

Key Point:
Indicates how “peaky” the waveform is compared to its average.
Higher form factor means more power content for the same average value.
2. Peak Factor (Crest Factor)
Definition:
The peak factor (or crest factor) is the ratio of the peak (maximum) value to the RMS value of a waveform.
Peak Factor=VPeak/VRMS

Key Point:
Measures the sharpness or extremes in the waveform.
Important in designing insulation and protective devices in electrical systems.
Power factor12:43
Star delta connection and Relation between current and Voltage33:28
In three-phase electrical systems, the two common methods of connecting loads or windings are the Star (Y) and Delta (Δ) configurations. In a Star connection, one end of each of the three components is connected to a common neutral point, and the other ends are connected to the line conductors. This setup allows both line-to-line and line-to-neutral voltages to be accessed, making it suitable for systems requiring dual voltage levels. In Star, the line voltage is root(3) times the phase voltage, and the line current equals the phase current.
On the other hand, in a Delta connection, the three components are connected end-to-end to form a closed loop resembling a triangle. Each corner of the triangle is connected to a line conductor, and there is no neutral point in this configuration. In Delta, the line voltage is equal to the phase voltage, but the line current is sqrt(3) times the phase current. Delta connections are commonly used in power transmission and motor applications due to their higher current-carrying capability and ability to deliver more power without a neutral wire. Both configurations have specific advantages and are often used in combination depending on the application requirements
Delta Voltage22:31
A Delta (Δ) connection is one of the two main ways to connect three-phase electrical systems, the other being Star (Y). In a delta network, the ends of three components (like windings or resistors) are connected in a triangle (Δ) shape.
Phasor diagram11:21
A phasor is a graphical and mathematical tool used to represent alternating current (AC) quantities like voltage and current, which vary sinusoidally with time. It helps in analyzing AC circuits by converting time-varying sinusoidal waveforms into rotating vectors in the complex plane.
Definition:
A phasor is a complex number that represents the magnitude and phase of a sinusoidal quantity.
AC through pure Resistance22:02
Properties of AC Through a Pure Resistor:
Current and voltage are in phase (i.e., both reach their maximum and zero values at the same time).
Power is continuously consumed as heat (real power).
Ohm’s Law is followed:
I=V/R
No reactance (opposition due to frequency) — only resistance limits current.
The waveform of current is identical to voltage (if voltage is sinusoidal, current is also sinusoidal).
Power factor is 1 (unity), meaning all supplied power is used effectively.
No energy is stored; it is fully dissipated as heat.
Resistor does not affect frequency or phase of the AC signal.
Used in heaters, lamps, and electronic circuits for controlling current.
Power (P) = V × I = I²R = V²/R — all represent real (active) power.
AC through Pure Capacitance25:29
Properties of AC Through Pure Capacitance:
Current leads voltage by 90° (phase lead).
No real power is consumed; only reactive power is involved.
Energy is alternately stored and released by the capacitor.
Capacitive reactance (X) opposes current flow, and is inversely proportional to frequency:
XC=1/2πfC
Higher frequency → Lower reactance → More current.
Current is maximum when voltage changes fastest (at zero crossing).
Voltage is maximum when current is zero (at peak charge).
Only displacement current flows, not conduction current.
Used in AC filters, tuning circuits, and power factor correction.
Pure capacitive circuits do not dissipate energy as heat.
AC through Pure Inductance34:52
Voltage leads current by 90° (phase lead).
No real power is consumed; only reactive power is involved.
Energy is stored and released in the magnetic field of the inductor.
Inductive reactance (XL) opposes current flow, and is directly proportional to frequency:
XL=2πfL
Higher frequency → Higher reactance → Less current.
Current is maximum when voltage changes slowly (at zero voltage crossing).
Voltage is maximum when current changes fastest (at current zero crossing).
Only alternating current flows, no DC passes through (after initial transient).
Used in chokes, filters, and transformers in AC circuits.
Pure inductive circuits do not dissipate energy as heat, but cause power factor lag.

Requirements

Course is started form Scratch therefor any body can learn who has passed 10th or 12 exams

Description

Basics of Electrical Engineering (First Year, SPPU)

Introduction to Electrical Engineering
- Overview of Electrical Engineering
- Applications of Electrical Engineering in Various Fields
Electric Circuits and Components
- Basic Circuit Concepts: Voltage, Current, and Power
- Types of Electrical Components: Resistors, Capacitors, Inductors, and Switches
- Series and Parallel Circuits
Ohm’s Law and Its Applications
- Understanding Voltage, Current, and Resistance
- Solving Simple Circuits Using Ohm's Law
- Power and Energy in Electrical Circuits
Kirchhoff's Laws
- Kirchhoff's Current Law (KCL)
- Kirchhoff's Voltage Law (KVL)
- Applications of KCL and KVL in Circuit Analysis
Electromagnetic Theory
- Introduction to Magnetism and Electromagnetism
- Magnetic Field, Flux, and Induction
- Faraday's Law of Electromagnetic Induction
AC and DC Circuits
- Alternating Current (AC) and Direct Current (DC)
- Sinusoidal Waveforms and Frequency
- Impedance and Reactance in AC Circuits
Basic Electrical Machines
- Introduction to Electrical Machines: Generators and Motors
- Principles of Operation of DC Motors and Generators
- Basics of Transformers
Power Generation and Transmission
- Sources of Electrical Energy: Thermal, Hydro, and Renewable
- Basics of Power Generation, Transmission, and Distribution
- Overview of Power Systems and Electrical Grids
Superposition Theorem
- Principle of Superposition for Linear Circuits
- Application in Solving Circuits with Multiple Sources
Complex Numbers in Electrical Engineering
- Introduction to Complex Numbers
- Use of Complex Numbers in AC Circuit Analysis
- Phasors and Impedance Representation

Who this course is for:

This course is for First year students of Savitribai Phule University Pune (SPPU)
It also used for student preparing Exam like BMC, RTO, DISCOM, TRANSCO, GENCO

Basics of Electrical Engineering, First year, SPPU

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Course content

Elementary Concepts and DC13 lectures • 6hr 31min

Electromagnetism15 lectures • 5hr 51min

AC fundamental11 lectures • 4hr 31min

AC circuit15 lectures • 6hr 55min

Transformer and Induction motor9 lectures • 3hr 22min

Requirements

Description

Who this course is for: