Physics
Electrical Energy
Electrical energy is the energy produced by the movement of electrons through a conductor. It is a form of kinetic energy that can be harnessed to power various devices and systems. Electrical energy is fundamental to the functioning of modern technology and is generated through processes such as electromagnetic induction and chemical reactions in batteries.
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11 Key excerpts on "Electrical Energy"
eBook - PDFThe Electronics Companion
Devices and Circuits for Physicists and Engineers, 2nd Edition
- Anthony C. Fischer-Cripps(Author)
- 2014(Publication Date)
- CRC Press(Publisher)
1 Electricity 1 1. Electricity 1. Electricity Summary 2 2 1 d q q k F E q F 1 A Q k E 4 Force between two charges where Force on a charge in a field Electric field - point charge o 4 1 k 2 ˆ r r q k E EA ) ( ) ( 2 2 2 1 1 1 v n q v n q A I dt dq i Ed q W V 1 Electric field - point charge Electric flux Electric current Electric potential R I V R I VI P 2 A R l d A V Q C o l 2 o N A L 2 2 1 CV U 2 2 1 LI U 2 1 2 1 2 1 1 1 1 R R R R R R R R AB AB 2 1 R R R AB Ohm's law Power - resistor Resistivity Capacitance Inductance Energy - capacitor Energy - inductor Resistors - series Resistors - parallel 2 1 1.1 Electricity The Electronics Companion 2 Consider a circuit in which a battery is connected to a light bulb through a switch. Light & heat energy + Chemical energy Switch In this simple electrical system, chemical energy is converted into Electrical Energy in the battery. The Electrical Energy travels along the wires to the light bulb where it is converted into heat and light. The switch is used to interrupt the flow of Electrical Energy to the light bulb. Although such an electrical system may seem commonplace to us now, it Electrical Energy was only invented about 100 years ago. For thousands of years before this, light and heat were obtained by burning oil or some other combustible fuel (e.g., wood). Although the concept of electric charge was known to the ancient Greeks, and electricity as we know it was well-studied in the 19th century, it remained a scientific curiosity for many years until it was put to use in an engineering sense. In the early part of the 20th century, electrical engineering was concerned with motors, generators and generally large scale electrical machines. In the second half of the 20th century, advances in the understanding of the electronic structure of matter led to the emergence of the new field of l t i I iti ll l t i i it b ilt d l ti l l electronics.
eBook - PDF- Charles A. Gross, Thaddeus A. Roppel(Authors)
- 2012(Publication Date)
- CRC Press(Publisher)
There is of course no shortage of energy in the universe . Indeed, the universe is composed of only two enti-ties: matter and energy! 2 Broadly speaking, one can classify energy as being either potential or kinetic: that is, an object possesses energy by virtue of its position (“potential energy”) or of its motion (“kinetic energy”) . Energy can appear in various forms, including: Mechanical Thermal, or heat Chemical Electrical Electromagnetic (radiant) Sound energy Nuclear energy Humanity needs energy for lighting, heating, transportation, manufacturing, construction, and, sad to say, destruction . To direct energy to human needs, it is necessary to easily control it and convert it from one form to another, which prompts us to address a key question: Why study energy in the electrical form? Electrical Energy is important because (1) it is relatively simple to convert into (and from) any other form, and (2) it is also simple to move it between two locations! Also, once energy is in the electrical form, we can subject it to incredibly complicated control . Think of the sophisticated control necessary to create a TV picture, refreshed at a rate of at least thirty times per second! Consider the conversion of the kinetic energy of falling water to electricity, 1 The other three being length, time, and charge or current . 2 Excluding consideration of a spiritual presence, which is beyond the scope of our study .
eBook - PDF- Giovanni Saggio(Author)
- 2014(Publication Date)
- CRC Press(Publisher)
29 Physical and Electrical Background Electronics is defined as the scientific study of the behavior and design of elec-tronic devices and circuits, based on some fundamental physical and electrical definitions. 2.1 FORCE, WORK, ENERGY, POWER The (mechanical) force arrowrightnosp F refers to any (physical) cause capable of modifying the condition of constant speed of a body (note that even a stationary body has a constant speed, equal to zero), or of deforming it. The SI unit of force is the Newton [ N ] ( Sir Isaac Newton, an English physicist, mathematician, astronomer, natu-ral philosopher, alchemist, and theologian, 1642–1727, Figure 2.1). A force arrowrightnosp F acting on a body of mass m causing its move-ment along a distance d , produces a work W : W Fd = arrowrightnosp The ability of a (physical) system to work on another (physical) system is known as energy ( E ), a scalar physical quantity. 2 FIGURE 2.1 I. Newton. Principles of Analog Electronics 30 The SI unit of energy is the Joule [ J ] ( James Prescott Joule, English physicist, 1818–1889 , Figure 2.2). It follows that for a mechanical work, with no other energy-transfer processes involved, the result is Δ E = W . But the energy can be generally transferred from one system to the other in different forms, as heat ( Q ), radiation , motion , sound ,… so the general form is E W Q E ∆ = + + where E represents other additional advected energy terms. Curiosities Kinetic energy is derived from the Greek term kinema , meaning “movement,” from which the term cinema is also derived. Coriolis ( Gaspard-Gustave de Coriolis, French math-ematician, mechanical engineer and scientist, 1792– 1843 , Figure 2.3) coined the term work to represent the transfer of energy by a force acting through a distance.
No longer available |Learn more- (Author)
- 2014(Publication Date)
- Learning Press(Publisher)
• Electric potential : the capacity of an electric field to do work on an electric charge, typically measured in volts. • Electromagnetism : a fundamental interaction between the magnetic field and the presence and motion of an electric charge. The most common use of the word electricity is less precise. It refers to: • Electric power provided commercially by the electrical power industry. In a loose but common use of the term, electricity may be used to mean wired for electricity which means a working connection to an electric power station. Such a connection grants the user of electricity access to the electric field present in electrical wiring, and thus to electric power. Electrical phenomena have been studied since antiquity, though advances in the science were not made until the seventeenth and eighteenth centuries. Practical applications for electricity however remained few, and it would not be until the late nineteenth century that engineers were able to put it to industrial and residential use. The rapid expansion in electrical technology at this time transformed industry and society. Electricity's extraordinary versatility as a source of energy means it can be put to an almost limitless set of applications which include transport, heating, lighting, communications, and computation. Electrical power is the backbone of modern industrial society, and is expected to remain so for the foreseeable future. History Thales, the earliest researcher into electricity Long before any knowledge of electricity existed people were aware of shocks from electric fish. Ancient Egyptian texts dating from 2750 BC referred to these fish as the Thunderer of the Nile, and 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.
- Andrei D. Polyanin, Alexei Chernoutsan(Authors)
- 2010(Publication Date)
- CRC Press(Publisher)
Chapter E6 Electrical Engineering E6.1. Generalities E6.1.1. Introduction. Basic Notions, Definitions, and Notation ◮ Preliminary remarks. Electrical engineering is a technical science studying physical phenomena related to directed motion of charged particles in conducting media at the level of macroprocesses and the problems of practical use of such phenomena. Electrical engineering is traditionally divided into the following fields: foundations of circuit theory, foundations of magnetic circuits, electric devices and transformers, electric machines, and foundations of electronics. The basic notions of electrical engineering coincide with similar notions in the course of physics. Electrical engineering employs the following physical quantities in the sense explained below. ◮ Notions, definitions, and notation. The potential is the work done by electric forces to transfer the unit charge from a given point in space, in particular, a given point of the circuit to the point at infinity (the zero potential point). The potential is denoted by the symbol ϕ and is measured in volts (V). The potential can be determined for a given point in space (circuit) with respect to the zero potential. The voltage ( potential difference ) is the work done by electric forces to transfer the unit charge from a point in space (circuit) to another point. The voltage is also measured in volts (V) and denoted by the symbol U . The voltage can be determined only between two points in space (circuit). The current strength ( current ) is the electric charge passing through the conductor transverse cross-section per unit time. The current strength is measured in amperes (A) and is denoted by I . The current strength can be determined for a given element of the electric circuit. The electromotive force (EMF) is the work done by forces of nonelectrostatical nature (extraneous forces) to transfer the unit charge from a point in space (circuit) to another point.
eBook - PDFElectrical Principles & Practice NQF3 SB
TVET FIRST
- Jowaheer Consulting and Technologies(Author)
- 2014(Publication Date)
- Macmillan(Publisher)
The unit of power is named after him. 15 Module 1 Fundamental concepts of electricity Energy Energy is the ability to do work. When work is done on an object, it gains energy. If work is done by an object, it loses energy. The unit for energy is the joule (J). Electric energy is the result of power developed over a certain period of time. Energy is calculated using the formula: E = Pt where: E = energy in joules (J) P = power in watts (W) t = time in seconds (s) Joule’s Law When current flows through a resistor, heat is produced. This concept is known as Joule’s Law. Joule’s Law states that the heat produced by the current flow through a conductor is directly proportional to the square of the current, the resistance and time. Written as a mathematical expression, Joule’s Law is: Q = I ² Rt where: Q = the amount of heat generated in joules (J) I = the current flowing in the circuit in amperes (A) t = time in seconds (s) R = resistance in ohms (Ω) An electrical kettle consumes 1,8 MJ when connected across a 230 V supply for 30 minutes. Calculate the current drawn from the supply and the power rating of the kettle. Given : E = 1,8 MJ; V = 230 V; t = 30 min Solution P = E __ t = 1,8 × 10 6 _______ 30 × 60 = 1 000 W or 1 kW (power rating of the kettle) Since P = VI I = P __ V I = 1 000 _____ 230 I = 4,348 A (current drawn from the supply) Example 1.6 energy: the ability to do work, measured in joules (J). Words & Terms Electrical appliances are often given a power rating. The power rating, in watts (W), shows the rate at which the appliance changes Electrical Energy into another form of energy such as light, heat or movement. In some appliances the power or wattage rating shows the maximum power the appliance is designed to use. For example, a 60 W bulb uses 60 W when operated at the voltage specified on the bulb. Think about it Did you know? James Prescott Joule (1818–1889) was an English physicist.
eBook - PDF- Richard L. Myers(Author)
- 2005(Publication Date)
- Greenwood(Publisher)
Electricity 239 opposite directions. The increase in electrical potential energy in separating the charge from the plate is qEd. In this example, it is assumed that the electrical potential at the surface of the plate is zero. The equation for electrical potential energy is analogous to gravitational potential energy (Figure 13.7). In the latter case the work done against the gravitational field when a mass, m, is lifted is —mgh, and the mass acquires a gravita- tional potential energy of mgh. The electri- cal potential energy increases by q Ed when a test charge is separated from a negative plate defined as having a potential energy of zero. In this example, the negative plate was defined as having an electrical potential energy of zero. In many cases, zero electri- cal potential energy is considered zero at the Earth's surface. It should be remembered that just as gravitational potential energy can be defined using any reference level, that electrical potential energy could use any ref- erence. In many cases, the Earth's surface is the most logical reference level to establish zero gravitation potential energy, and ground to establish electrical potential energy. The electrical potential energy depends on the value of the test charge. More charge will require a greater amount of work to move against the electrical field, just as it takes a greater amount of work to move a greater mass against a gravitational field. The amount of electrical potential energy divided by the charge is defined as the electrical potential at that point in the electric field. The unit for electrical poten- tial energy is the joule and for charge is the coulomb. The SI unit for electrical potential is joules per coulomb and is defined as the volt, named in honor of Volta. A 12 V bat- tery has the potential to give 12 J of energy to every coulomb of charge flowing through the battery. Another way of interpreting electrical potential is in terms of the amount of work.
eBook - PDF- Michael Brumbach(Author)
- 2016(Publication Date)
- Cengage Learning EMEA(Publisher)
Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. 32 CHAPTER 3 Electrical Energy Electrical Energy is the product of power and time. Therefore, its unit of measurement is the watt-hour (Wh), or the kilowatt-hour (kWh). A 100-watt incandescent lamp will utilize 1 kWh of energy if it is operated for 10 hours (100 W 3 10 hours 5 1000 Wh 5 1 kWh). Electrical consumers are billed by the utility company according to the amount of energy uti-lized. In other words, they are billed for the amount of power expended in a specific period of time. Bill-ing is usually based on a sliding scale according to the number of kilowatt-hours indicated for the bill-ing period. Example 4 The customer, an industrial plant, expends 5000 kWh of Electrical Energy each working day. The plant is in operation 5 days per week. If the utility company charges $0.03 per kWh for the first 50,000 kWh and $0.015 per kWh for all energy above 50,000 kWh, how much does the customer pay for a 10-week period? 5000 kWh/day 3 5 days/week 3 10 weeks 5 250,000 kWh 50,000 kWh 3 $0.03/kWh 5 $1500.00 250,000 kWh 2 50,000 kWh 5 200,000 kWh 200,000 kWh 3 $0.015/kWh 5 $3000.00 $1500.00 1 $3000.00 5 $4500.00 paid for the 10-week period EFFICIENCY Efficiency is the ratio of the useful power output to the total power input. Efficiency is generally stated in percent (%). No machine is 100% efficient. Not all the energy delivered to a machine serves the purpose for which it was intended. A motor is de-signed to produce motion (mechanical energy); however, some of the Electrical Energy received by the motor produces heat. The energy that is con-verted into heat is considered a loss.
eBook - PDF- John D. Cutnell, Kenneth W. Johnson, David Young, Shane Stadler(Authors)
- 2021(Publication Date)
- Wiley(Publisher)
578 CHAPTER 19 Electric Potential Energy and the Electric Potential 19.1 Potential Energy In Chapter 18 we discussed the electrostatic force that two point charges exert on each other, the magnitude of which is F = k∣q 1 ∣∣q 2 ∣/r 2 . The form of this equation is similar to the form for the gravitational force that two particles exert on each other, which is F = Gm 1 m 2 /r 2 , according to Newton’s law of universal gravitation (see Section 4.7). Both of these forces are conservative and, as Section 6.4 explains, a potential energy can be associated with a conservative force. Thus, an electric potential energy exists that is analogous to the gravitational potential energy. To Lightning permeates the sky around the ash plume above the Puyehue-Cordon Caulle volcano in south-central Chile in 2011. Unlike normal lightning associated with rain clouds, where static charges are produced by colliding ice particles, volcanic lightning, or “dirty thunderstorms,” can result from frictional charging between colliding ash and dust particles. The natural convective thermal currents in the hot ash cloud aid in the separation of charges. This creates extremely high differences in voltage, or potential, between different parts of the dust cloud or between the cloud and the ground. If the voltage difference is sufficiently large, the insulating properties of the air break down, and it conducts electricity in spectacular fashion. The electric potential, and its relationship to charge, will be one of the topics we study in this chapter. Carlos Gutierrez/Reuters LEARNING OBJECTIVES After reading this module, you should be able to... 19.1 Define electrical potential energy. 19.2 Solve problems involving electric potential and electric potential energy. 19.3 Calculate electric potential created by point charges. 19.4 Relate equipotential surfaces to the electric field. 19.5 Solve problems involving capacitors. 19.6 Describe biomedical applications of electric potential.
eBook - PDF- John D. Cutnell, Kenneth W. Johnson, David Young, Shane Stadler(Authors)
- 2018(Publication Date)
- Wiley(Publisher)
The quantity EPE/q 0 is the electric potential energy per unit charge and is an important concept in electricity. It is called the electric potential or, simply, the potential and is referred to with the symbol V, as in Equation 19.3. DEFINITION OF ELECTRIC POTENTIAL The electric potential V at a given point is the electric potential energy EPE of a small test charge q 0 situated at that point divided by the charge itself: V = EPE q 0 (19.3) SI Unit of Electric Potential: joule/coulomb = volt (V) The SI unit of electric potential is a joule per coulomb, a quantity known as a volt. The name honors Alessandro Volta (1745–1827), who invented the voltaic pile, the forerunner of the battery. In spite of the similarity in names, the electric potential energy EPE and the electric potential V are not the same. The electric potential energy, as its name implies, is an energy and, therefore, is measured in joules. In contrast, the electric potential is an energy per unit charge and is measured in joules per coulomb, or volts. Initial gravitational, potential energy, GPE A { Final gravitational potential energy, GPE B { h A F = mg F = mg h B A B FIGURE 19.1 Gravity exerts a force, F → = m g → , on the basketball of mass m. Work is done by the gravitational force as the ball falls from A to B. q 0 F = q 0 E q 0 F = q 0 E A B − − − − − − − − − − − − − − + + + + + + + + + + + + + + INTERACTIVE FIGURE 19.2 Because of the electric field E → , an electric force, F → = q 0 E → , is exerted on a positive test charge +q 0 . Work is done by the force as the charge moves from A to B. 19.2 The Electric Potential Difference 525 We can now relate the work W AB done by the electric force when a charge q 0 moves from A to B to the potential difference V B − V A between the points.
- S. B. Lal Seksena, Kaustuv Dasgupta(Authors)
- 2017(Publication Date)
- Cambridge University Press(Publisher)
Prerequisite knowledge Current electricity of +2 standard Static electricity of +2 standard 1.1 Introduction The recorded observations related to various electrical events and facts are found dating back to the fifth century BC. The lighting in a stormy night, or the attraction between a rubbed amber and cat’s fur have always provoked human curiosity. But, it was merely a subject of the philosopher’s mind, rather than the business of technology. It was only in the mid-sixteenth century that scientists developed techniques to store electrical charge. Suddenly, like a flash of thunder, everything was changed. We were able to convert a spontaneous event into a continuous operation. The technology had shifted from the era of the mechanical intentions to the era of electrical progression. We can call it a paradigm shift of technology. Like any other paradigm shift, this change did not occur overnight. We have achieved the great electrical inventions through gradual efforts by scientists. Different theories and formulae had made it possible. In this chapter, we are going to discuss these preliminary concepts and related theories to begin with, starting with static electrical charges to laws of current electricity. We shall also observe that the application of these theories requires a great deal of measurement and quantification of various electrical parameters, such as electrical potential, current flow and resistance. Let us explore this world of electricity from the perspective of an electrical engineer. 1.2 Charge Electrical charge is the fundamental concept of electricity. In a mechanical system ‘the matter’ matters, for an electrical system the charge takes all the charges. We conceptualize our materialistic world as an accumulation of particles. In the electrical domain, it is the charge of a particle; we are more concerned about it. Every atom is constituted of a number of charges. There are two types of charges which play major roles in electricity.
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