Basic Electrical Engineering Notes
By Saifullah Siddique
Electrical Terminology:-
● AC (Alternating Current) : A type of electric current that periodically changes
its direction and magnitude.
● DC (Direct Current): A type of electric current that flows in one direction only.
● Voltage: The electric potential difference between two points, measured in
volts (V).
● Current: The flow of electric charge, measured in amperes (A).
● Resistance: The opposition to the flow of electric current, measured in ohms
(Ω).
● Capacitance: The ability of a component to store electric charge, measured
in farads (F).
C=Q/V
Where C is capacitance (farads), Q is charge (coulombs), and V is voltage
(volts).
● Inductance: The property of an electrical conductor by which a change in
electric current through it induces an electromotive force (voltage) in the
conductor, measured in henrys (H).
Inductance formula (for a solenoid):
L = (μ * N^2 * A) / l
Where L is inductance (henrys), μ is the permeability of the core material
(henry per metre), N is the number of turns, A is the cross-sectional area of
the coil (square metres), and l is the length of the coil (meters).
● Impedance: The total opposition to the flow of alternating current, which
includes both resistance and reactance, measured in ohms (Ω).
Z = √(R^2 + (X_L - X_C)^2)
Where Z is impedance (ohms), R is resistance (ohms), X_L is inductive
reactance (ohms), and X_C is capacitive reactance (ohms).
,● Power: The rate at which work is done or energy is transferred, measured in
watts (W).
Power formulas:
P=V*I
P = I^2 * R
P = V^2 / R
Where P is power (watts), V is voltage (volts), I is current (amperes), and R is
resistance (ohms).
● Transformer: A device that transfers electrical energy between two or more
circuits through electromagnetic induction.
Transformer formulas:
N_primary / N_secondary = V_primary / V_secondary = I_secondary /
I_primary
Where N_primary and N_secondary are the number of turns in the primary
and secondary coils, respectively; V_primary and V_secondary are the
primary and secondary voltages, respectively; and I_primary and I_secondary
are the primary and secondary currents, respectively.
● Circuit: A closed path through which an electric current flows.
● Ohm's Law: The fundamental relationship between voltage, current, and
resistance in an electric circuit, given by V = IR.
V=I*R
Where V is voltage (volts), I is current (amperes), and R is resistance(ohms)
● Kirchhoff's Laws: Two fundamental principles that describe the relationships
between currents and voltages in an electrical circuit.
Kirchhoff's Current Law (KCL):
ΣI_in = ΣI_out
The sum of currents entering a node is equal to the sum of currents
leaving the node.
● Transistor: A semiconductor device used to amplify or switch electronic
signals and electrical power.
● Diode: A semiconductor device that allows current to flow in one direction
only.
● Capacitor: An electronic component that stores and releases electrical
energy.
,● Inductor: An electronic component that stores energy in a magnetic field
when electric current flows through it.
● Integrated Circuit (IC): A set of electronic circuits on a single, small chip of
semiconductor material.
● Oscillator: An electronic circuit that produces a periodic, oscillating signal,
such as a sine wave or square wave.
● Rectifier: A device that converts alternating current (AC) to direct current
(DC).
● Relay: An electrically operated switch that uses an electromagnet to
mechanically operate a set of contacts.
● Fuse: A safety device that protects an electrical circuit by melting and
breaking the circuit when the current exceeds a specified value.
● Circuit Breaker: A safety device that automatically interrupts the flow of
current in an electric circuit when an overload or short circuit occurs.
● Ground: A common reference point for an electrical system, often connected
to the Earth.
● Three-Phase Power: A common method of generating, transmitting, and
distributing electric power using three separate alternating currents that are
120 degrees out of phase with each other.
● Earthing: In the context of electrical systems, earthing generally refers to
connecting the non-current-carrying metallic parts of an electrical installation
(such as the frames of machines or metallic enclosures) to the earth. The
primary purpose of earthing is to minimize the risk of electric shock and
protect people and equipment from potential hazards. When a fault occurs,
such as insulation failure or short circuit, earthing ensures that the fault
current is safely diverted to the ground, preventing the metallic parts from
becoming live (energized). Earthing also helps maintain the voltage stability of
the system and can reduce the risk of damage from voltage surges, such as
those caused by lightning strikes.
● Grounding: Grounding typically refers to the process of connecting the
current-carrying conductors, such as neutral conductors, of an electrical
system to the earth. Grounding ensures a stable reference point for the
system's voltage levels and provides a return path for the fault currents. By
creating a low-resistance path to the ground, grounding helps maintain the
, proper functioning of electrical systems and minimizes the risk of electrical
hazards, such as fires or equipment damage.
● Conductors: Materials that allow the flow of electric charge with low
resistance.
● Inductor: A passive electronic component that stores energy in a magnetic
field, typically consisting of a coil of wire.
● Power Factor: The ratio of real power (watts) to apparent power
(volt-amperes) in an AC circuit, indicating the efficiency of power usage.
● Electromotive Force (EMF): The force that causes the motion of electric
charge, creating an electric potential difference (voltage) in a circuit.
● Ground Fault Circuit Interrupter (GFCI): A safety device that quickly breaks
an electrical circuit when it detects an imbalance between the incoming and
outgoing current, protecting against electric shock.
● Electric Motor: A device that converts electrical energy into mechanical
energy, usually by means of electromagnetic forces.
● Electric Generator: A device that converts mechanical energy into electrical
energy, usually by means of electromagnetic induction.
● Power Electronics: The study and application of solid-state electronic
devices for controlling and converting electrical power.
● Control Systems: The study of systems that regulate, command, or control
the behavior of other systems, using feedback.
● Digital Signal: A signal that represents information as a sequence of discrete
values, often binary (0 and 1).
● Analog Signal: A continuous signal that can take on any value within a
specified range.
● Electromagnetic Induction: The process of generating an electromotive
force (EMF) in a conductor due to a changing magnetic field.
● Load: The electrical component or components connected to a power source
that consume electrical energy.
By Saifullah Siddique
Electrical Terminology:-
● AC (Alternating Current) : A type of electric current that periodically changes
its direction and magnitude.
● DC (Direct Current): A type of electric current that flows in one direction only.
● Voltage: The electric potential difference between two points, measured in
volts (V).
● Current: The flow of electric charge, measured in amperes (A).
● Resistance: The opposition to the flow of electric current, measured in ohms
(Ω).
● Capacitance: The ability of a component to store electric charge, measured
in farads (F).
C=Q/V
Where C is capacitance (farads), Q is charge (coulombs), and V is voltage
(volts).
● Inductance: The property of an electrical conductor by which a change in
electric current through it induces an electromotive force (voltage) in the
conductor, measured in henrys (H).
Inductance formula (for a solenoid):
L = (μ * N^2 * A) / l
Where L is inductance (henrys), μ is the permeability of the core material
(henry per metre), N is the number of turns, A is the cross-sectional area of
the coil (square metres), and l is the length of the coil (meters).
● Impedance: The total opposition to the flow of alternating current, which
includes both resistance and reactance, measured in ohms (Ω).
Z = √(R^2 + (X_L - X_C)^2)
Where Z is impedance (ohms), R is resistance (ohms), X_L is inductive
reactance (ohms), and X_C is capacitive reactance (ohms).
,● Power: The rate at which work is done or energy is transferred, measured in
watts (W).
Power formulas:
P=V*I
P = I^2 * R
P = V^2 / R
Where P is power (watts), V is voltage (volts), I is current (amperes), and R is
resistance (ohms).
● Transformer: A device that transfers electrical energy between two or more
circuits through electromagnetic induction.
Transformer formulas:
N_primary / N_secondary = V_primary / V_secondary = I_secondary /
I_primary
Where N_primary and N_secondary are the number of turns in the primary
and secondary coils, respectively; V_primary and V_secondary are the
primary and secondary voltages, respectively; and I_primary and I_secondary
are the primary and secondary currents, respectively.
● Circuit: A closed path through which an electric current flows.
● Ohm's Law: The fundamental relationship between voltage, current, and
resistance in an electric circuit, given by V = IR.
V=I*R
Where V is voltage (volts), I is current (amperes), and R is resistance(ohms)
● Kirchhoff's Laws: Two fundamental principles that describe the relationships
between currents and voltages in an electrical circuit.
Kirchhoff's Current Law (KCL):
ΣI_in = ΣI_out
The sum of currents entering a node is equal to the sum of currents
leaving the node.
● Transistor: A semiconductor device used to amplify or switch electronic
signals and electrical power.
● Diode: A semiconductor device that allows current to flow in one direction
only.
● Capacitor: An electronic component that stores and releases electrical
energy.
,● Inductor: An electronic component that stores energy in a magnetic field
when electric current flows through it.
● Integrated Circuit (IC): A set of electronic circuits on a single, small chip of
semiconductor material.
● Oscillator: An electronic circuit that produces a periodic, oscillating signal,
such as a sine wave or square wave.
● Rectifier: A device that converts alternating current (AC) to direct current
(DC).
● Relay: An electrically operated switch that uses an electromagnet to
mechanically operate a set of contacts.
● Fuse: A safety device that protects an electrical circuit by melting and
breaking the circuit when the current exceeds a specified value.
● Circuit Breaker: A safety device that automatically interrupts the flow of
current in an electric circuit when an overload or short circuit occurs.
● Ground: A common reference point for an electrical system, often connected
to the Earth.
● Three-Phase Power: A common method of generating, transmitting, and
distributing electric power using three separate alternating currents that are
120 degrees out of phase with each other.
● Earthing: In the context of electrical systems, earthing generally refers to
connecting the non-current-carrying metallic parts of an electrical installation
(such as the frames of machines or metallic enclosures) to the earth. The
primary purpose of earthing is to minimize the risk of electric shock and
protect people and equipment from potential hazards. When a fault occurs,
such as insulation failure or short circuit, earthing ensures that the fault
current is safely diverted to the ground, preventing the metallic parts from
becoming live (energized). Earthing also helps maintain the voltage stability of
the system and can reduce the risk of damage from voltage surges, such as
those caused by lightning strikes.
● Grounding: Grounding typically refers to the process of connecting the
current-carrying conductors, such as neutral conductors, of an electrical
system to the earth. Grounding ensures a stable reference point for the
system's voltage levels and provides a return path for the fault currents. By
creating a low-resistance path to the ground, grounding helps maintain the
, proper functioning of electrical systems and minimizes the risk of electrical
hazards, such as fires or equipment damage.
● Conductors: Materials that allow the flow of electric charge with low
resistance.
● Inductor: A passive electronic component that stores energy in a magnetic
field, typically consisting of a coil of wire.
● Power Factor: The ratio of real power (watts) to apparent power
(volt-amperes) in an AC circuit, indicating the efficiency of power usage.
● Electromotive Force (EMF): The force that causes the motion of electric
charge, creating an electric potential difference (voltage) in a circuit.
● Ground Fault Circuit Interrupter (GFCI): A safety device that quickly breaks
an electrical circuit when it detects an imbalance between the incoming and
outgoing current, protecting against electric shock.
● Electric Motor: A device that converts electrical energy into mechanical
energy, usually by means of electromagnetic forces.
● Electric Generator: A device that converts mechanical energy into electrical
energy, usually by means of electromagnetic induction.
● Power Electronics: The study and application of solid-state electronic
devices for controlling and converting electrical power.
● Control Systems: The study of systems that regulate, command, or control
the behavior of other systems, using feedback.
● Digital Signal: A signal that represents information as a sequence of discrete
values, often binary (0 and 1).
● Analog Signal: A continuous signal that can take on any value within a
specified range.
● Electromagnetic Induction: The process of generating an electromotive
force (EMF) in a conductor due to a changing magnetic field.
● Load: The electrical component or components connected to a power source
that consume electrical energy.
