Understanding key concepts of Electric Circuits
Electric Circuit
Electric circuits are closed loops or routes that connect electrical components and allow
electrons to flow. This road is comprised of electrical cables and powered by a source, such as a
battery. The source is the point from which electrons begin to flow, and the return is the point at
which electrons depart the electrical circuit.
Electric Circuit Symbols
Every component and product of the electric circuit has a symbol. In a circuit diagram, the
symbols correspond to circuit components. The fundamental symbols used in a circuit diagram are
shown below.
Simple Circuit
A simple circuit comprises the power source, conductors, switch, and load.

Cell: It is the power source.

Load: It is also termed as the resistor. It is a light bulb that lights when the circuit is
turned on.

Conductors: They are composed of copper wires with no insulation. One end of the wire
links the load to the power source, while the other end connects the power source to the
load.

Switch: It is a small gap in the circuit. There are various types of switches. A switch can
be used to open or close a circuit.
Types of Electric Circuits:
There are following 5 main types of electric circuit
1. Close Circuit
A closed circuit is a form of electrical circuit in which electricity can flow without
interruption or breakdown. Batteries, switches, and lights are some of the components
found in closed circuits.
Example of a closed circuit:
Basic Closed Circuit
There are no breakages or obstacles in the circuit that prevent electricity from
passing through all components and complete the circuit. The electricity is permitted to
circulate around the circuit, powering the lamp.
Closed Circuit with a switch
The graphic shows another closed circuit, this time with two bulbs, a power supply,
and a switch. The switch is closed, which allows current to flow from the power supply to
both bulbs.
If we open the switch or remove one of the terminations, the circuit will change
from closed to open. Both bulbs would be unable to function because of the lack of current
supply.
2. Open Circuit
An open circuit is an electrical circuit that does not allow current to flow. In a
circuit, current can only flow if it finds a continuous path—this is known as a "closed
circuit." An open circuit occurs when there is a break somewhere in the circuit and current
cannot flow.
3. Short Circuit
A short circuit is an unwanted or accidental path that current might travel that
skips the desired paths. A short circuit is essentially a low resistance connection between
two conductors that provide electrical power to any circuit.
4. Series Circuit
A series circuit is a basic electrical circuit with a single route for electricity to
travel.
Example:
Series circuit with a battery and three resistors.
5. Parallel Circuit
A parallel circuit is an electrical configuration where components are connected in
multiple paths, allowing current to flow through more than one path simultaneously
Example: Parallel circuit with a battery and three resistors
RESISTANCE
Resistance measures the obstacle to current flow in an electrical circuit. It is influenced by
the material's qualities, including length, cross-sectional area, and temperature.
Factors Affecting Electrical Resistance
The electrical resistance of a conductor is dependent on the following factors:

The cross-sectional area of the conductor

Length of the conductor

The material of the conductor

The temperature of the conducting material
Electrical resistance is directly related to the conductor’s length (L) and inversely
proportional to its cross-sectional area. It is determined by the following relationship.
R= pL/A
where ρ is the resistivity of the material (measured in Ωm, ohm meter)
Examples of Resistance:

In a toaster, current flows through small coils, generating heat to brown bread.

Incandescent light bulbs force current through thin filaments, producing light.

A piece of wire has resistance.

Electric irons have resistance.

Lamps in series have greater resistance.
CONDUCTOR
An electrical conductor is described as a substance that allows electricity to pass through
it. The ability of conductors to carry electricity is known as conductivity.
Examples of conductor
Graphite, the human body, and the earth are good conductors of electricity. Some of the
common conductor examples include metals such as:

Copper

Gold

Iron

Steel

Aluminum

Brass
Types of Electrical conductors:
1. Ohmic Conductors
Ohmic conductors are materials that follow Ohm's law at any potential difference
and temperature. They have a linear connection between voltage and current, hence their
resistance is constant. Most metals are ohmic conductors under normal conditions.
2. Non- Ohmic Conductors
Non-ohmic conductors are materials that do not follow Ohm's law at any potential
difference or temperature. They feature a nonlinear connection between voltage and
current, therefore their resistance fluctuates with applied voltage.
Non-ohmic conductors can have negative resistance, which means the current
reduces as the voltage increases, or positive resistance, which means the current increases
as the voltage increases but not proportionately. Some non-ohmic conductors may also
have a threshold voltage below which no current may flow.
Key characteristics of electrical conductors
Important features of an electrical conductor include the following:

It ensures free movement of electrons or ions through it.

It has a zero electric field inside, which permits the movement of electrons or ions.

Outside the conductor, the electric field is perpendicular to the conductor's surface.

It has a zero-charge density, ensuring that the positive and negative charges cancel each
other, and free charges exist only on the surface.
Conductors have both low resistance and good heat conductivity. Furthermore, a conductor
put in a magnetic field does not retain energy. Finally, both ends of the conductor have the same
potential. When the potential at one end of the conductor changes, electricity flows across it,
allowing electrons to travel from one end to the other.
INSULATOR
Insulators are materials that restrict electricity from passing easily through them. This
means they may be used to interrupt the flow of electricity in a circuit and protect people and
objects from electrical shock.
Examples for Insulators are given below:

Plastic

Rubber

Wax

Wood

Glass

Air

Styrofoam
General properties that affect the effectiveness of an insulator are:

High resistivity as we have already discussed

Breakdown voltage

Atomic structure

Air permeability
Types of insulators:
There are mainly five types of insulators, such as:

Suspension insulators - An insulator that acts as a conductor to protect an overhead
transmission cable is called a suspension insulator.

Strain insulators - String insulators are utilized whenever a suspension string is needed to
support a high tensile pressure on some kind of conductor.

Pin insulators - The first ceiling-mounted insulators to be created, and they've been widely
employed in power networks up to 33 kV is called pin insulators.

Stay insulators - A type of low voltage insulator used to balance and secure the dead-end
pole using stay wire or guy grip is called stay insulators.

Shackle insulators - An insulator that is utilized in low voltage distribution networks is
called a shackle insulator.
Insulators are most utilized in applications that require the blocking of the flow of electric
charges. These materials function as effective nonconductors because they lack the moveable
electric charges necessary to propagate electric current.
Electrical insulators are mainly used as components of electrical equipment. For example, to
reduce safety issues, electrical lines that transport power through residences are wrapped with
insulating material. The electrical plugs feature an insulating coating that prevents electricity from
traveling from the metal socket (conductor) to your body (also a conductor) by blocking the
passage of electrons.
References:
Cope, L. (2022). Closed Circuit: Definition, Uses and FAQs. Engineer Fix.
https://engineerfix.com/electrical/circuits/closed-circuit-definition-uses-andfaqs/#google_vignette
Cope, L. (2022). What is a Series Circuit? Advantages and Disadvantages and
Examples.
Engineer
Fix.
https://engineerfix.com/electrical/circuits/what-is-a-series-
circuit/#google_vignette
Das, S. (2021). Electric Circuit-Types of Electric Circuit. Electronic and you.
https://www.electronicsandyou.com/blog/electric-circuit-types-of-electric-circuit.html
Electrical Conductors: Definition, Types, and Properties. (May 6, 2024). E4U.
https://www.electrical4u.com/electrical-conductor/
Linquip Team (March 4, 2023). What is Open Circuit? Diagram & Example. Linquip
Technews. https://www.linquip.com/blog/what-is-open-circuit/
Series Circuits and the Application of Ohm’s Law. (n.d.). ALL ABOUT CIRCUITS.
https://www.allaboutcircuits.com/textbook/direct-current/chpt-5/simple-series-circuits/
Parallel Circuits and the Application of Ohm’s Law. (n.d.). ALL ABOUT CIRCUITS.
https://www.allaboutcircuits.com/textbook/direct-current/chpt-5/simple-parallel-circuits/
What Are Electric Circuits. (n.d.). ALL ABOUT CIRCUITS.
https://www.allaboutcircuits.com/textbook/direct-current/chpt-1/electric-circuits/
What is Electrical Resistance and types of Resistances. (June 6, 2024). Circuitschools.
https://www.circuitschools.com/what-is-electrical-resistance/
BU102
Building Utilities: Electrical and Mechanical
System
Research Paper No. 1
Understanding Key Concepts of Electric Circuits
NAME: MASONGSONG, ERICA MAY M.
SECTION: A014B
SCHEDULE: WED 12:30 P.M.- 3:30 P.M.
PROFESSOR: AR. NUELLE G. NOBLEZA