Basic Electrical and Electronics Engineering

Basic Electrical and Electronics Engineering (EE 420)

• This text provides an overview of basic electrical and electronics engineering concepts.

Learning Objectives

• Grasp basic electrical engineering principles, concepts, laws, and theorems.
• Discern the characteristics of direct current systems.
• Apply Ohm's Law along with mathematical formulas for basic electrical problem-solving.
• Determine the effect of temperature on resistance
• Comprehend electrical circuits and employ voltage, current, and resistance equations.

Electricity

• Electricity involves the flow of electrons in a closed circuit to perform work.
• Electricity is a form of energy that can be converted.
• Electricity constitutes the flow of electrons in a circuit.
• Electricity is related to the Greek word "electron," meaning amber.
• Electrons is the the fundamental cause of electricity

Two Main Types of Electricity

• Static Electricity involves electrons moving between places through rubbing or brushing.
• Static Electricity results from the contact between equal amounts of protons and electrons.
• For friction to work, particles must have opposite charges (+, -).
• Current Electricity involves electron flow in a conductor.
• Current Electricity is a flow of charge across an electrical field.
• Conductors can be good, like copper, or bad, like wood.
• Continuous charge flow often heats the conductor

Electricity's History

• Around 600 BC, Greeks observed that rubbing amber against fur attracted straw particles.
• Around 1600, William Gilbert studied magnetism, determined Earth is a magnet.
• Gilbert named the attraction produced when materials were rubbed "electric".
• The word "electricity" is derived from named attraction discovered by Gilbert

William Gilbert

• William Gilbert is the "father of electricity."
• Gilbert coined the term "electricity," referencing the Greek word for Amber.

Benjamin Franklin

• In 1752, Franklin proved lightning and sparks from amber are electrical.
• Franklin attached an iron spike to a kite flown during a thunderstorm.
• A spark jumped from the kite's key to his wrist.
• Franklin proved his theory, but it was extremely dangerous.

Galvani and Volta Timeline

• In 1786, Luigi Galvani found that frog legs twitched when touched by a metal knife, suspecting muscles contain electricity.
• By 1792, Alessandro Volta disagreed with Galvani and realized that two different metals caused leg twitches.
• Volta discovered that electricity is created when moisture is between two metals.
• Volta invented the first electric battery from copper and zinc sheets separated by moist pasteboard.
• Volta discovered this new electricity flowed steadily, not just in a single shock.
• Volta showed electricity travels via wires, a valuable contribution.
• The "Volt," the unit of electrical potential, is named after Volta.

Michael Faraday

• Michael Faraday discovered a practical way to generate electric current.
• Electricity can produce magnetism, so Faraday wondered if magnetism could produce electricity.
• In 1831, Faraday found electricity could be produced through magnetism by motion.
• A magnet moving inside a copper wire coil generates a tiny electric current.
• Faraday invented the first electric generator.
• Faraday also discovered that the electric force is transmitted by an electric field.

James Watt

• When Edison's generator was combined with Watt's steam engine, large-scale electricity generation was practical.
• James Watt, a Scottish inventor of the steam condensing engine, was born in 1736 and improved steam engines.
• Watt's improvements to steam engines were patented over 15 years starting in 1769.
• The electric unit of power, the "Watt," was named after James Watt.

Andre Marie Ampere

• Andre Marie Ampere, a French mathematician, dedicated himself to study of electricity and magnetism.
• Ampere is credited as the the first to explain the electro-dynamic theory.
• The unit of electric current, the "Ampere", is named after him.

George Ohm

• George Simon Ohm, a German mathematician and physicist.
• In 1827, Ohm published "The Galvanic Circuit Investigated Mathematically".
• Ohm's theories, initially unaccepted, were recognized in Britain and awarded the Copley Medal in 1841.
• The unit of electrical resistance, the "Ohm", has been named after George Ohm.

How Electricity is Produced

• Frictional Energy (Static Electricity)
• Pressure.
• Heat.
• Chemical Reaction.
• Light.
• Magnetism.

E. Electricity Produced from Light

• Light striking photosensitive materials produces electricity.
• These materials release electrons when excited by light under the right conditions which results in photoelectric effect.

Quick Review of the Atom

• Matter comprises atoms.
• Atoms consist of nucleons (protons, neutrons) and electrons.
• Protons carry a positive charge, neutrons have no charge, and electrons have a negative charge.
• Protons' and electrons' charges are equal and opposite.
• Electrons move in and out of fixed pathways around the nucleus
• Altering the electron count in an atom results in an ion.
• Electrons are more loosely bound in the outer shells of atoms.
• Free electrons tend to break free from the nucleus.

Matter

• Anything occupying space and possessing weight.

Element

• A substance that cannot be chemically broken down.

Atom

• Smallest amount of an elements that retains its chemical properties.
• It is the smallest building block of matter.

Compound

• Combination of two or more elements.

Electrons

• Negatively charged particles around an atom's nucleus.
• One of the lightest known particles with mass.
• Electron mass: approximately 9.11 x 10^-31 kg.

Protons

• Positively charged particles residing in the atomic nucleus
• Protons are small but massive compared to other particles.
• One proton's mass measures 1.675 x 10^-27 kg.

Neutrons

• Particles having no charge which are about the same size as protons with a slightly greater mass which is 1.675 x 10^-27 kg

Nucleus

• The nucleus is where protons and neutrons reside.

Atomic Number

• This represents the quantity of electrons or protons in an atom.

Atomic Mass

• The sum of protons and neutrons determine Atomic Mass.

Conductors

• Electric charges move freely through conductors but not insulators.
• Charge carriers in conductors are free electrons.
• Only negative charges move freely.
• Metal atoms' outer electrons freely move rather than attaching to the atoms.

Other Types of Conductors

• Electrolytes allow both negative and positive charges to move.
• Semiconductors have conductivity between conductors and insulators.
• Semiconductor conductivity can greatly increase by adding small amounts of other elements.
• Quantum physics is needed to understand how semiconductors function.

Insulators

• Insulators oppose conductors.
• Insulators are made of non-metals that have very few free electrons
• Electrons are firmly bound to inner nucleus.
• Insulators prevent current flow when voltage is applied.
• Examples are marble, p.v.c plastics, rubber, glass,oil, asphalt, fiberglass, porcelain, ceramic, dry cotton, dry copper, dry wood, air, diamond, mica, textile fiber, and wax.
• Insulators help to avoid risk of circuits shorting by isolating components.
• Overhead transmission cables use insulators made of glass or porcelain.
• Printed circuit boards employ epoxy glass resin.

Systems of Units

• Defining consistent units needed for representing circuits and their elements.
• The General Conference of Weights and Measures modernized the metric system in 1960.
• The result was le Système International d'Unités (SI units).

SI Prefixes

• exa (E): 10^18
• peta (P): 10^15
• tera (T): 10^12
• giga (G): 10^9
• mega (M): 10^6
• kilo (k): 10^3
• deci (d): 10^-1
• centi (c): 10^-2
• milli (m): 10^-3
• micro (μ): 10^-6
• nano (n): 10^-9
• pico (p): 10^-12
• femto (f): 10^-15
• atto (a): 10^-18

Direct Current System

• Direct current (DC): An electric current that is unidirectional (flow of charge is always in the same direction).
• Amperage of direct currents do not change.
• DC current is used in many household electronics and in all devices that use batteries

Electric Circuit Theory

• Fundamental theory upon which electrical engineering is built.
• Electric circuit theory is basis of power, electric machines, control, electronics, communications, etc.

Electric Circuit

• It is a series of interconnected electrical components, each identified as an element.
• A simple electric circuit: battery, light bulb, connecting wires, and a switch

Types of Electric Circuit

• Open Circuit: Two detached terminals exhibit infinite resistance; no current flows regardless of voltage.
• Closed Circuit: An electric circuit is always a closed path that is complete with continuity throughout
• Short Circuit: Two externally linked terminals show zero resistance; at any current value, voltage is zero.

Electrical Symbols

• Electrical symbols represent components in circuit diagrams.
• Symbols include: Wire, Resistor, Light bulb, Cell, Battery, Switch, Voltmeter, Capacitor, Ammeter and Inductor

Basic Electrical Engineering Instruments

• Ammeter: Measures current, connects in series, has low resistance.
• Voltmeter: Measures potential difference, connects in parallel, has high resistance.
• Wattmeter: Measures power in an electrical circuit.
• Ohmmeter: Measures resistance.
• Multimeter: Measures voltage, current, and resistance.

Circuit Variables

• Electric Charge: Matter's atomic particles have electrical properties and are measured in Coulombs (C).
• Like charges repel, unlike charges attract.
• 1 coulomb (C )= 6.24 x 10^18 electrons or protons -Q is charge in Coulumbs(C), I is Current in Amperes (A), t is time in seconds (s)

Electric Current

• Electric current is created by the movement of free electrons.
• Materials that contain large numbers of free electrons is called electrical conductors.
• Electric current is a measure of electron/electric charge flow.
• it is measured in amperes (A) or Coulombs/sec/
• Q is charge in Coulombs(C), I is Current in Amperes (A), t is time in seconds (s)

Types of Current

• Direct Current (DC): A current that remains constant over time.
• Alternating Current (AC): A current that varies sinusoidally with time.

Voltage

• Voltage is the work or energy per unit charge to overcome attraction/repulsion between charges.
• Voltage goes by other names and measured in volts (V)
• To move a unit charge through an element, energy is required. -Work done is V = dW/dq, 1volt = 1 joule/coulomb = 1newton - meter / coulomb
• W is work, Q is Charge

Types of Voltage

• DC Voltage - Consistently produced by batteries.
• AC Voltage - Typically produced by electric generators.

Power

• Power indicates energy usage/absorption rate, with "watt" being the unit for power.
• The wattage is the equivalent to on joule of energy consumed in one second.
• Watt was named after the British engineer and inventor James Watt.
• Power P = VI, and PR =

How Circuits Supply/Absorb Power

• The power absorbed or supplied by an element is the product of the voltage and current
• When current goes into the positive voltage terminal, p = +vi
• When current goes into the negative voltage terminal p= -vi.
• p = +vi means the element absorbs power.
• p = -vi means the element supplies power.

Electrical Energy

• Energy is the capacity to do work W.
• W= electrical energy (joule)
• P= electrical power (watt)
• t= time (second)
• Kilowatt-hour (kW-hr) is a unit in which electrical energy is sold to a consumer. -1 calorie= 4.186 joules, 1 hp = 746 watts, 1 BTU= 252 calories, 1 kWh= 3600 kJ= 3413 BTU =860 kcal, 1 joule= 1 x ergs, 1 day = 24 hours, 1 month = 30 days = 720 hours, 1 year = 365 days = 8760 hours

Passive Circuit Elements

• Circuits components described as impeding flow of current or electric charge.
• It's capacity to do this is called resistance, and measured in ohms(Ω).

Types of Resistors

• Fixed value Resistors: resistor which offers a fixed amount of resistance in the circuit.
• Variable Resistors: In which the value of resistance is not fixed.
• Potentiometer: Contains 3 terminals and a rotating shaft which changes the value of resistance.

Law of Resistance

• Resistance varies directly with length (I).
• Resistance varies inversely with cross-sectional area (A).
• Resistance depends on the nature and temperature of the material.

Specific Resistance

• The resistance of electrical materials in terms of unit dimensions length and cross sectional area,
• It is also the amount of change of resistance in a material per unit change in temperature.
• Resistance = pL/A where volume V = pV/A^2 or pL^2/V
• R = Resistance, A = Cross-sectional area, p = Resistivity, L = Length, V = Volume
• Resistance is directly proportional to conductor length.
• The resistance is inversely proportional to the cross sectional area.

Common Elements

• The text lists various common materials and their respective resistivity (ρ), temperature coefficient (T), and α at 20°C.

Circular Mil (CM)

• The area of a circle with a diameter of one mil, where mil is thousandth of an inch,
• where 1 in = 1,000 mils, 1 MCM=1,000 CM
• Measured with A=d^2 where d = diameter in mil

Square Mil

• A unit of cross-sectional area where sides are equal to 1 mil
• A = S^2
• Conversion formula to square mil is ASM = π/4 ACM

Temperature

• Rise in temperature – increases the R of pure metals or alloys but decreases the R of electrolytes and insulators
• R2/R1 = T + T2/T + T1
• Absolute temperature is R2 where R2 = R1 (R₁ = initial resistance, R₂ = final resistance, T =inferred absolute T =temperature where resistance vanishes, per degree per ohm
• A change in temperature of a material, which dictates ohmic change
• Copper Annealed = 234.5, Silver = 243 and Alumium = 236

Conductors Undergoing Drawing Process

• In the process, the waste of the material is assumed negligible (efficiency is 100%), thus keeping the volume to be constant all throughout the process.
• R2/R1 = (L2/L1)^2 =(A1/A2) = (d1 /d2)4

Resistor Color Code

• Manufacturers use the resistor color code to indicate resistance and tolerance.
• Tolerance is the amount that code varies from the color-coded value.

Inductor

• The Inductor is a passive element designed to store energy in its magnetic field
• It consists of a coil of conducting wire which is fixed or variable in construction with a core that is made of iron, steel, plastic, or air,.
• Inductors used in Electronics and power systems plus power Supplies, Transformers, Radios, TVs

Capacitor

• The capacitor is a passive element designed to store energy in an electric field
• It consists of two conducting plates separated by an insulator or dielectric which is air, ceramic, paper or mica
• Capacitors are used in Tuning Circuits of Radio Receivers dynamic memory elements used to block dc, pass ac, shift phase, store energy, start motors and suppress noise.

Ohm’s Law

• The definition of Ohm's law is the current in in an electric circuit is directly proportional to the voltage inversely to the resistance of the said circuit. named for the German physicist, Georg S. Ohm.
• Formula is V = IR