History Of Electricity And How Does It Work

Electricity is a fascinating field where the interplay of physical phenomena associated with electric charges creates a world of possibilities. As someone with hands-on experience and a deep-rooted interest in this domain, I've dedicated significant time and effort to understanding its intricacies.

My career has spanned various industries, including manufacturing, pharmaceuticals, and oil and gas, where I've honed my electrical troubleshooting skills. Roles such as Service Engineer for power press machinery and Instrument Technician in the oil and gas sector have equipped me with a comprehensive understanding of electrical systems. While these experiences were invaluable, the repetitive nature of such roles can be stifling. I thrive on challenges and find fulfilment in devising innovative solutions to complex electrical problems.

Beyond the technical realm, I've ventured into acting, demonstrating my adaptability and willingness to explore diverse fields. This unconventional path has enriched my problem-solving approach, making me versatile.

Let's delve deeper into the captivating world of ELECTRICITY.

Electricity is related to magnetism, both being part of the phenomenon of electromagnetism, as described by Maxwell's equations. Common phenomena are related to electricity, including lightning, static electricity, electric heating, electric discharges, etc.

The presence of either a positive (+) or negative (-) electric charge produces an electric field. The motion of electric charges is an electric current and produces a magnetic field. In most applications, Coulomb's law determines the force acting on an electric charge. Electric potential is the work done to move an electric charge from one point to another within an electric field, typically measured in volts.

Electricity plays a central role in many modern technologies, serving in electric power where electric current is used to energise equipment, and in electronics dealing with electrical circuits involving active components such as vacuum tubes, transistors, diodes and integrated circuits, and associated passive interconnection technologies.

The study of electrical phenomena dates back to antiquity, with theoretical understanding progressing slowly until, the 17th and 18th centuries. The development of the theory of electromagnetism in the 19th century marked significant progress, leading to electricity's industrial and residential application by electrical engineers by the century's end. This rapid expansion in electrical technology at the time was the driving force behind the Second Industrial Revolution, with electricity's versatility driving transformations in both industry and society. Electricity is integral to applications spanning transport, heating, lighting, communications, and computation, making it the foundation of modern industrial society.

Maxwell's Equations: The Heart of Electromagnetism

Maxwell's equations are a set of 4 fundamental equations that describe the behaviour of electric and magnetic fields. These equations are the cornerstone of classical electromagnetism, providing a mathematical framework to understand phenomena ranging from electric circuits to light and radio waves.   

The Four Equations:

While the complete mathematical representation involves complex calculus, we can break down the core concepts of each equation:

1. Gauss's Law for Electricity: This equation relates electric charge to the electric field it produces. Essentially, it states that electric field lines originate from positive charges and terminate at negative charges.  
2. Gauss's Law for Magnetism: This equation indicates that magnetic field lines always form closed loops, meaning there are no isolated magnetic poles (like magnetic monopoles).
3. Faraday's Law of Induction: This law describes how a changing magnetic field induces an electric field. It's the principle behind electromagnetic induction, the basis for generators and transformers.   
4. Ampère's Law with Maxwell's Addition: This equation relates electric currents and changing electric fields to the magnetic field they produce. Maxwell's addition to Ampère's law was crucial, introducing the concept of displacement current, which is essential for understanding electromagnetic waves. 

Historically, the finding of electricity is a collaboration of scientists' finding throughout millennia: 

Long before any knowledge of electricity existed, people were aware of shocks from electric fish. Ancient Egyptian texts dating from 2750 BCE described them as the "protectors" of all other fish. Electric fish were again reported millennia later by ancient Greek, Roman and Arabic naturalists and physicians. Several ancient writers, such as Pliny the Elder and Scribonius Largus, attested to the numbing effect of electric shocks delivered by electric catfish and electric rays and knew that such shocks could travel along conducting objects. Patients with ailments such as gout or headache were directed to touch electric fish in the hope that the powerful jolt might cure them.

Ancient cultures around the Mediterranean knew that certain objects, such as rods of amber, could be rubbed with a cat's fur to attract light objects like feathers. Thales of Miletus made a series of observations on static electricity around 600 BCE, from which he believed that friction rendered amber magnetic, in contrast to minerals such as magnetite, which needed no rubbing. Thales was incorrect in believing the attraction was due to a magnetic effect, but later science would prove a link between magnetism and electricity. According to a controversial theory, the Parthians may have had knowledge of electroplating, based on the 1936 discovery of the Baghdad Battery, which resembles a galvanic cell, though it is uncertain whether the artefact was electrical in nature. Electricity would remain little more than an intellectual curiosity for millennia until 1600, when the English scientist William Gilbert wrote De Magnete, in which he made a careful study of electricity and magnetism, distinguishing the lodestone effect from static electricity produced by rubbing amber. He coined the Neo-Latin word electricus ("of amber" or "like amber", from ἤλεκτρον, Elektron, the Greek word for "amber") to refer to the property of attracting small objects after being rubbed. This association gave rise to the English words "electric" and "electricity", which made their first appearance in print in Thomas Browne's Pseudodoxia Epidemica of 1646.

Later in the 18th century, Benjamin Franklin conducted extensive research in electricity, selling his possessions to fund his work. In June 1752 he is reputed to have attached a metal key to the bottom of a dampened kite string and flown the kite in a storm-threatened sky. A succession of sparks jumping from the key to the back of his hand showed that lightning was indeed electrical in nature. He also explained the apparently paradoxical behaviour of the Leyden jar as a device for storing large amounts of electrical charge in terms of electricity consisting of both positive and negative charges. In 1775, Hugh Williamson reported a series of experiments to the Royal Society on the shocks delivered by the electric eel; that same year the surgeon and anatomist John Hunter described the structure of the fish's electric organs. In 1791, Luigi Galvani published his discovery of bioelectromagnetics, demonstrating that electricity was the medium by which neurons passed signals to the muscles.

Alessandro Volta's battery, or voltaic pile, of 1800, made from alternating layers of zinc and copper, provided scientists with a more reliable source of electrical energy than the electrostatic machines previously used. The recognition of electromagnetism, the unity of electric and magnetic phenomena, is due to Hans Christian Ørsted and André-Marie Ampère in 1819–1820. 

Michael Faraday invented the electric motor in 1821, and Georg Ohm mathematically analysed the electrical circuit in 1827. Electricity and magnetism (and light) were definitively linked by James Clerk Maxwell, in particular in his "On Physical Lines of Force" in 1861 and 1862.

While the early 19th century had seen rapid progress in electrical science, the late 19th century would see the greatest progress in electrical engineering. Through such people as Alexander Graham Bell, Ottó Bláthy, Thomas Edison, Galileo Ferraris, Oliver Heaviside, Ányos Jedlik, William Thomson, 1st Baron Kelvin, Charles Algernon Parsons, Werner von Siemens, Joseph Swan, Reginald Fessenden, Nikola Tesla and George Westinghouse, electricity turned from a scientific curiosity into an essential tool for modern life.

In 1887, Heinrich Hertz:  discovered that electrodes illuminated with ultraviolet light create electric sparks more easily. In 1905, Albert Einstein published a paper that explained experimental data from the photoelectric effect as being the result of light energy being carried in discrete quantized packets, energising electrons. This discovery led to the quantum revolution. Einstein was awarded the Nobel Prize in Physics in 1921 for "his discovery of the law of the photoelectric effect". The photoelectric effect is also employed in photocells such as can be found in solar panels.

The first solid-state device was the "cat's-whisker detector" first used in the 1900s in radio receivers. A whisker-like wire is placed lightly in contact with a solid crystal (such as a germanium crystal) to detect a radio signal by the contact junction effect. In a solid-state component, the current is confined to solid elements and compounds engineered specifically to switch and amplify it. Current flow can be understood in two forms: as negatively charged electrons, and as positively charged electron deficiencies called holes. These charges and holes are understood in terms of quantum physics. The building material is most often a crystalline semiconductor.

Solid-state electronics came into its own with the emergence of transistor technology. The first working transistor, a germanium-based point-contact transistor, was invented by John Bardeen and Walter Houser Brattain at Bell Labs in 1947, followed by the bipolar junction transistor in 1948. 

Electricity at the particle level is the Flow of Electrons

Electricity is a form of energy resulting from the movement of charged particles, primarily electrons. It's a fundamental force of nature, powering everything from simple light bulbs to complex electronic devices. 

Electron Is A Subatomic Particle

With a negative charge. It is one of the fundamental building blocks of matter, along with protons and neutrons. Electrons orbit the nucleus of an atom, which is composed of protons and neutrons.

 

These electrons act differently in their behaviour in different materials (characteristic)  

 his is a fundamental property of the particle.  The charge of a single electron is approx = -1.602 x 10^-19 coulombs. 

Electrons Are Building Blocks of the Current

As we've established, electrons are subatomic particles with a negative charge. They are the fundamental particles responsible for electric current. 

Electric Current Are The Flow of Electrons

Electric current is the rate of flow of electric charge. Essentially, it's the movement of electrons through a conductor.  

• The direction of flow: While electrons physically move from the negative to the positive terminal of a battery, conventionally, current is considered to flow from positive to negative. This is a historical convention that doesn't affect circuit analysis.  
• Measurement: Electric current is measured in amperes (A). One ampere is equal to one coulomb of charge passing a point in one second.  

Factors That Affects Current:

• Voltage: The potential difference between two points in a circuit, measured in volts (V), drives the flow of electrons. A higher voltage results in a higher current.  
• Resistance: The opposition to the flow of electric current in a material, measured in ohms (Ω). Higher resistance reduces current flow.  

Ohm's Law relates these quantities:

• Voltage (V) = Current (A) * Resistance (Ω)

 

The man behind Ohm Law: 

Georg Simon Ohm was a German physicist who is credited with formulating Ohm's Law. Through meticulous experimentation, Ohm discovered a fundamental relationship between voltage, current, and resistance in an electrical circuit.  

 

Ohm's law states that the electric current through a conductor between two points is directly proportional to the voltage across the two points. Introducing the constant of proportionality, the resistance, one arrives at the three mathematical equations used to describe this relationship: 

Where I is the current through the conductor, V is the voltage measured across the conductor and R is the resistance of the conductor. More specifically, Ohm's law states that the R in this relation is constant, independent of the current. If the resistance is not constant, the previous equation cannot be called Ohm's law, but it can still be used as a definition of static/DC resistance. Ohm's law is an empirical relation which accurately describes the conductivity of the vast majority of electrically conductive materials over many orders of magnitude of current.

Resistive circuits

Resistors are circuit elements that impede the passage of electric charge in agreement with Ohm's law and are designed to have a specific resistance value R. In schematic diagrams, a resistor is shown as a long rectangle or zig-zag symbol. An element (resistor or conductor) that behaves according to Ohm's law over some operating range is referred to as an ohmic device (or an ohmic resistor) because Ohm's law and a single value for the resistance suffice to describe the behaviour of the device over that range.

Ohm's law holds for circuits containing only resistive elements (no capacitances or inductances) for all forms of driving voltage or current, regardless of whether the driving voltage or current is constant (DC) or time-varying such as AC. At any instant of time, Ohm's law is valid for such circuits.

Resistors which are in series or in parallel may be grouped together into a single "equivalent resistance" to apply Ohm's law in analyzing the circuit.

Electrical Unit Conversions

Before diving into conversions, let's review the fundamental electrical units:

• Voltage (V): Measures the potential difference between two points in an electrical circuit.
• Current (A): Measures the rate of flow of electric charge.   
• Resistance (Ω): Measures the opposition to the flow of electric current.   
• Power (W): Measures the rate at which energy is transferred.   
• Energy (Wh or kWh): Measures the total amount of energy consumed.

Common Conversions

Electrical unit conversions and their formulas:

Power (W)

• Watts to Kilowatts (kW): 1 kW = 1000 W  
• Watts to Horsepower (hp): 1 hp ≈ 746 W

Energy (Wh or kWh)

• Watt-hours to Kilowatt-hours (kWh): 1 kWh = 1000 Wh
• Kilowatt-hours to Joules (J): 1 kWh = 3.6 x 10^6 J  

Current (A)

• Amperes to Milliamperes (mA): 1 A = 1000 mA
• Amperes to Kiloamperes (kA): 1 kA = 1000 A

Useful Conversion Formulas

• Ohm's Law: V = IR (Voltage = Current * Resistance)  
• Power Law: P = VI (Power = Voltage * Current)   
• Energy: E = Pt (Energy = Power * Time)  

Fundamental Laws of Electricity

Electrical laws are the foundational principles governing the behaviour of electric charges and currents. They provide the framework for understanding and analyzing electrical circuits.  

 

The Key of Electrical Laws:

• Ohm's Law: Relates voltage, current, and resistance in a circuit (V = IR).  
• Kirchhoff's Laws:
• Kirchhoff's Current Law (KCL): The total current flowing into a junction is equal to the total current flowing out of it.  
• Kirchhoff's Voltage Law (KVL): The sum of all voltages around a closed loop in a circuit is equal to zero.  
• Joule's Law: Relates the heat generated by an electrical current to the resistance, current, and time.  

Coulomb's Law: Describes the force between two electric charges.   

• Faraday's Law of Induction: Explains electromagnetic induction.  
• Lenz's Law: Determines the direction of induced current.
• Maxwell's Equations: A comprehensive set of equations describing electric and magnetic fields.  

There are two types of Current: 

Direct Current (DC)

• Constant flow: Electrons move in a single direction.  
• Sources: Batteries, solar cells, and DC power supplies.  
• Applications: Electronic devices, rechargeable batteries, and control systems.

Alternating Current (AC)

• Reversing flow: Electrons change direction periodically.  
• Sources: Power plants, electrical grids.
• Applications: Powering homes, businesses, and industries.

Role Of Rectifier: 

AC to DC conversion is essential for powering electronic devices that require a steady, unidirectional current. This process is achieved primarily through the use of rectifiers.   

AC Waveforms:

While we've established that AC power typically follows a sinusoidal waveform, it's essential to grasp other key characteristics:

• Peak Voltage (Vp): The maximum voltage value reached during a cycle.
• Peak-to-Peak Voltage (Vpp): The difference between the maximum positive and negative peaks.
• Root Mean Square (RMS) Voltage (Vr): The equivalent DC voltage that produces the same heating effect. This is the value typically used for power calculations.
• Frequency: The number of cycles per second, measured in Hertz (Hz). 

AC Power Calculations

Using RMS values, we can apply Ohm's law and power formulas similar to DC calculations:

• Power (P) = Vrms * Irms
• Current (Irms) = Vrms / R

AC Power Transmission and Distribution

DC Waveforms

Unlike AC waveforms, which oscillate over time, DC waveforms are characterized by their constancy.

An ideal DC waveform is a straight, horizontal line. It represents a constant voltage or current value over time. There are no fluctuations or changes in direction. 

Real-world DC Waveforms

In practical applications, perfect DC waveforms are difficult to achieve. There are often minor variations due to factors like:

• Ripple: Small fluctuations caused by the charging and discharging of capacitors in power supplies.
• Noise: Random fluctuations due to external interference.
• Load variations: Changes in the current draw can affect the voltage level.

DC waveform with ripple

Importance of DC Waveforms

Understanding DC waveforms is essential for:

• Power supply design: Ensuring stable and clean DC power for electronic devices.
• Circuit analysis: Identifying and mitigating noise or ripple in DC signals.
• Battery performance: Evaluating battery charging and discharging characteristics.

AC to DC Rectification

A rectifier is an electronic device that converts alternating current (AC), which periodically reverses direction, to direct current (DC), which flows in only one direction.  

How it works:

• Diodes: The core components of a rectifier are diodes, which allow current to flow in only one direction.  
• Half-wave rectifier: Uses a single diode to convert one half-cycle of the AC waveform into DC.  Full-wave rectifier: Employs four diodes to convert both halves of the AC waveform into DC, providing a smoother output.  

Rectification Process

1. AC input: The AC voltage is applied to the rectifier circuit.  
2. Diode conduction: During the positive half-cycle of the AC input, one or two diodes conduct, allowing current to flow through the load.
3. DC output: The output voltage is a pulsating DC, with a ripple component.     

Filtering:

To reduce the ripple in the output, a filter is often used. Capacitors are commonly employed for this purpose. The capacitor charges during the peak of the rectified waveform and discharges during the valleys, smoothing out the output. 

Types of Rectifiers

• Half-wave rectifier: Simpler but less efficient, with higher ripple. 
• Full-wave rectifier: More efficient, with lower ripple.   
• Bridge rectifier: A common type of full-wave rectifier using four diodes.

AC to DC conversion is essential in applications:

• Power supplies for electronic devices
• Battery chargers   
• Inverters (DC to AC conversion

Diode

A diode is a semiconductor device that essentially acts as a one-way switch for current. It allows current to flow easily in one direction but severely restricts current from flowing in the opposite direction. Which means it only allows electrons to flow in one direction. 

There are several types of diodes and its typical functions. 

Characteristics of Diode

The following are the characteristics of the diode:

• Forward-biased diode
• Reverse-biased diode
• Zero biased diode 

Forward-biased Diode

There is a small drop of voltage across the diode when the diode is forward-biased and the current is conducting. For silicon diodes, the forward voltage is 690mV and for germanium, 300mV is the forward voltage. The potential energy across the p-type material is positive and across the n-type material, the potential energy is negative.

Reverse-biased Diode

A diode is said to be reverse-biased when the battery’s voltage is dropped completely. For silicon diodes, the reverse current is -20μA and for germanium, -50μA is the reverse current.  The potential energy across the p-type material is negative and across the n-type material, the potential energy is positive.

Zero-biased Diode

When the diode is zero-biased, the voltage potential across the diode is zero.

Other More Diode's Application

• Diodes as a rectifier
• Diodes in the clipping circuit
• Diodes in clamping circuits
• Diodes in logical gates
• Diodes in reverse current protection

Logic Gates

Diode logic (or diode-resistor logic) constructs AND and OR logic gates with diodes and resistors.

An active device (vacuum tubes in early computers, then transistors in diode–transistor logic) is additionally required to provide logical inversion (NOT) for functional completeness and amplification for voltage level restoration, which diode logic alone can't provide.

Since voltage levels weaken with each diode logic stage, multiple stages can't easily be cascaded, limiting diode logic's usefulness. However, diode logic has the advantage of utilizing only cheap passive components.

7 PN Diode internal structure at zero bias

Logic gates evaluate Boolean algebra, typically using electronic switches controlled by logical inputs connected in parallel or series. Diode logic can only implement OR and AND because inverters (NOT gates) require an active device.

Binary logic uses two distinct logic levels of voltage signals that may be labelled high and low. In this discussion, voltages close to +5 volts are high, and voltages close to 0 volts (ground) are low. The exact magnitude of the voltage is not critical, provided that inputs are driven by strong enough sources so that output voltages lie within detectably different ranges.

For active-high or positive logic, high represents logic 1 (true) and low represents logic 0 (false). However, the assignment of logical 1 and logical 0 to high or low is arbitrary and is reversed in active-low or negative logic, where low is logical 1 while high is logical 0. The following diode logic gates work in both active-high or active-low logic, however, the logical function they implement is different depending on what voltage level is considered active. Switching between active-high and active-low is commonly used to achieve a more efficient logic design.

In summary, if any input is high the output will be high, but only if all inputs are low will the output below:

Inputs	Output
Low Low	Low
Low High	High
High Low	High
High High	High

AND Gate Truth Table:

A	B	Output
0	0	0
0	1	0
1	0	0
1	1	1

 

OR Gate Truth Table:

A	B	Output
0	0	0
0	1	1
1	0	1
1	1	1

 

NOT Gate: Outputs the opposite of the input (also known as an inverter). Truth Table:

A	Output
0	1
1	0

 

NAND Gate: Outputs false only if all inputs are true (NOT-AND). Truth Table:

A	B	Output
0	0	1
0	1	1
1	0	1
1	1	0

 

NOR Gate: Outputs true only if all inputs are false (NOT-OR). Truth Table:

A	B	Output
0	0	1
0	1	0
1	0	0
1	1	0

               

XOR Gate: Outputs true if inputs are different. Truth Table:

A	B	Output
0	0	0
0	1	1
1	0	1
1	1	0

 

XNOR Gate: Outputs true if inputs are the same (NOT-XOR). Truth Table:

A	B	Output
0	0	1
0	1	0
1	0	0
1	1	1

Logic Gates Samples 

Simple Series Circuit

Components:

• Battery: Provides the electrical energy.
• Resistor: Resists the flow of current (e.g., light bulb, LED, resistor).
• Connecting wires: Conduct the current.

Diagram:

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simple series circuit with a battery, resistor, and connecting wires

Explanation:

In a series circuit, the components are connected one after another. The current flows through each component sequentially. The total resistance of the circuit is the sum of the individual resistances.

Example: If you have a 9V battery and a 10 ohm resistor, the current flowing through the circuit would be:

Current (I) = Voltage (V) / Resistance (R) = 9V / 10 ohms = 0.9 amps