Physics
Energy Scale
The energy scale refers to a range of energy values used to describe various phenomena in physics. It provides a framework for understanding and comparing different energy levels, from subatomic particles to cosmic events. By using a standardized scale, physicists can analyze and interpret the behavior of particles and systems across different energy regimes.
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4 Key excerpts on "Energy Scale"
eBook - PDFThermodynamics
Fundamentals and Engineering Applications
- William C. Reynolds, Piero Colonna(Authors)
- 2018(Publication Date)
- Cambridge University Press(Publisher)
2 Energy CONTENTS 2.1 Concept of Energy 16 2.2 Microscopic Energy Modes 17 2.3 Internal Energy 18 2.4 Total Energy 18 2.5 Energy Transfer as Work 18 2.6 Energy Transfer as Heat 20 2.7 Energy Balances 22 2.8 Examples 23 Exercises 28 In the first chapter we reviewed the concept of energy as it arises in mechanical systems. We interpreted work as a transfer of energy and used this idea to develop expressions for kinetic and potential energy. These were special instances of the general concept of energy, which is perhaps the most fundamental concept in all of science. In thermodynamics, another relevant mode of energy transfer is heat. Once all these concepts are clear, they can be used together with the first law to analyze and design an infinite variety of systems and devices, which are at the foundation of current and future societies. 2.1 Concept of Energy The Energy Hypothesis The ideas inherent in the general concept of energy are encapsulated in what we call the Energy Hypothesis : Matter can be treated as having a property, called energy , that is an extensive, conserved scalar mea-suring its ability to cause change; work is a transfer of energy. The terms used above are very important: ● extensive means that the energy of a system is the sum of the energies of its parts; ● conserved means that the total amount of energy in an isolated system does not change; ● scalar means that energy is a quantity without directional (vector) character; ● work is a transfer of energy; it provides the key to the quantitative evaluation of the energy contained by matter. In Section 1.4 we used these ideas to obtain expres-sions for the kinetic and potential energy of matter. 2.2 Microscopic Energy Modes 17 Other energy forms are evaluated in the same way. Since the energy hypothesis is itself used in the evaluation and measurement of the energy of mat-ter, it is not possible to test the hypothesis of energy conservation by experimental measurements of energy.
eBook - PDFElectrons, Neutrons and Protons in Engineering
A Study of Engineering Materials and Processes Whose Characteristics May Be Explained by Considering the Behavior of Small Particles When Grouped Into Systems Such as Nuclei, Atoms, Gases, and Crystals
- J. R. Eaton(Author)
- 2013(Publication Date)
- Pergamon(Publisher)
CHAPTER 10 ENERGY LEVELS I N T R O D U C T I O N The quantum theory states that energy is transferred in small packets, the size of the packet being dependent on the characteristics of the system to which, or from which, the transfer takes place. It must not be inferred that the quanta of energy are of standardized size (as is the case with the electronic charge). Ac-tually quanta of every size are theoretically possible; the restrictions on size are set by the system which is asked to accept or to emit energy. In Chapter 5 the energy levels of atoms were discussed in considerable detail, with particular re-ference to the energy levels of the hydrogen atom. It was shown that the atom, the system made up of the nucleus with its complement of electrons, can accept energy from external sources only when the amount of energy supplied is equal to or greater than certain amounts characteristic of the particular element. Thus, the hydrogen atom can be excited from the ground state only when there is available a packet of energy having at least 10.19 eV of energy. In describing the behavior of energy absorption by atoms, it is stated that there are certain allowed energy levels between which are forbidden gaps. This quantization of energy levels applies not only to single atoms, but extends to the systems known as molecules and crystals. In fact the concept of energy levels becomes evident whenever two or more particles unite to form a more complicated aggregate. The study of the energy levels of groups of particles has many interesting and surprising ramifications. A knowledge of energy levels is necessary for an under-standing of such subjects as electrical conduction through gases, certain thermal properties of gases, electrical, thermal and optical properties of solids, chemical reactions, and even nuclear interactions.
eBook - PDFThermodynamics
A Smart Approach
- Ibrahim Dinçer(Author)
- 2020(Publication Date)
- Wiley(Publisher)
62 2 Energy Aspects being heated and boiled; this is clearly observed by eyes and makes it a nice example for macroscopic level of thermodynamics. In conjunction with the above given descriptions, one may categorize them into microscopic and macroscopic forms of energies as well. Mac-roscopic forms of energy are those where, in fact, we look deep into the internal energies and behavior of the material, such as those that are either measured or calculated based on the changes caused by kinetic and potential energies as shown in Figure 2.3b. In the macroscopic approach, one needs to consider three types of energy – internal energy, kinetic energy, and potential energy – under total energy ( E ) of a specific mass ( m ), which is the summation of these three energies as follows: E = U + KE + PE = mu + mV 2 2 + mgz kJ 2 1 Microscopic energy water water (a) (b) Macroscopic energy Figure 2.3 Illustration of (a) microscopic and (b) macroscopic energy behaviors. Thermodynamics Environment Energy Sustainability Figure 2.2 Thermodynamics as the heart of the three key domains of energy, environment, and sustainability. 2.2 Macroscopic Thermodynamics versus Microscopic Thermodynamics 63 where E denotes the total energy, U denotes the internal energy, KE denotes kinetic energy, PE is the potential energy, u is the specific internal energy, V is the velocity, g is the grav-itational acceleration (9.81 m / s 2 and 32.17 ft / s 2 ), and z is the elevation of the mass above the earth surface or the reference point. The total energy can also be presented in the specific form as follows: e = u + ke + pe = u + V 2 2 + gz kJ kg 2 2 Here, e denotes the specific total energy, u is the specific internal energy, ke is the specific kinetic energy and pe denotes the specific potential energy.
No longer available |Learn more- (Author)
- 2014(Publication Date)
- Academic Studio(Publisher)
The above list of the known possible forms of energy is not necessarily complete. Whenever physical scientists discover that a certain phenomenon appears to violate the law of energy conservation, new forms may be added, as is the case with dark energy, a hypothetical form of energy that permeates all of space and tends to increase the rate of expansion of the universe. Classical mechanics distinguishes between potential energy, which is a function of the position of an object, and kinetic energy, which is a function of its movement. Both position and move-ment are relative to a frame of reference, which must be specified: this is often (and originally) an arbitrary fixed point on the surface of the Earth, the terrestrial frame of reference. It has been attempted to categorize all forms of energy as either kinetic or potential: this is not incorrect, but neither is it clear that it is a real simplification, as Feynman points out: These notions of potential and kinetic energy depend on a notion of length scale. For example, one can speak of macroscopic potential and kinetic energy, which do not include thermal ______________________________ WORLD TECHNOLOGIES ______________________________ potential and kinetic energy. Also what is called chemical potential energy (below) is a macro-scopic notion, and closer examination shows that it is really the sum of the potential and kinetic energy on the atomic and subatomic scale. Similar remarks apply to nuclear potential energy and most other forms of energy. This dependence on length scale is non-problematic if the various length scales are decoupled, as is often the case ... but confusion can arise when different length scales are coupled, for instance when friction converts macroscopic work into microscopic thermal energy.
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