What does energy density mean in electricals?

Energy density is the amount of energy contained in a unit volume.

Electric and magnetic fields are distributed in the whole space, and they have energy, and these energies are unevenly distributed in the whole space, and the closer to the field source (i.e., charge or current) the energy of the field is denser—the more energy is contained in the unit volume; Conversely, the farther away from the field source, the sparser the field energy – the smaller the energy density.

Energy density is the amount of energy contained in a unit volume.

1: The external resistance overcome by the machine or active machine.

2: Requirements for the business capacity of a certain system (such as circuit switches, postal services, railways) 3: The weight to bear.

4: Power and current passing through wires, cables, and electrical equipment (transformers, circuit breakers, etc.).

The load or resistance that the muscles experience before contracting is called the preload. It is the muscle that has a certain initial length before contracting. Within a certain range, the tension produced by muscle contraction is directly proportional to the initial length of the muscle before contraction, and beyond a certain limit, it is inverse.

That is, in the initial stage, as the initial length increases, the muscle tone also increases; Muscles contract to produce maximum tension at the optimal initial length (optimal preload). When the initial length is increased, the muscle tone decreases. When the muscle is at the optimal initial length, if the isometric contraction begins, the shortening speed is the fastest, the shortening degree is the largest, and the workmanship efficiency is the highest.

Afterload refers to the load or resistance that muscles experience after they begin to contract. When the muscles contract under afterload, there is an increase in tension followed by the contraction of the muscles. Within a certain range, the greater the afterload, the greater the tension generated, and the slower the slowdown in the start of muscle reduction.

When the afterload increases to a certain value, the tension produced by the muscle reaches its maximum, and the muscle can not be shortened at all, the initial velocity is equal to zero, and the tension generated by the muscle is inversely related to the initial velocity when it contracts. Therefore, the muscles can only get the best results of their work when they are properly afterloaded.

Energy Density Formula Form of Magnetic Field and Electric Field:

Electric field energy density: e=1 2 d·e

Magnetic field energy density: m=1 2 b·h

d, electrical displacement, e, electric field strength, b, magnetic induction intensity, h, magnetic field strength. The equation is all vectors.

Ways to learn physics well:

1. Interested in physics. Physics is a very abstract subject, and many people don't like physics because it's difficult and abstract, especially for liberal arts students.

2. Or students who are partial to the subject, they hate the course of physics, and if they are not interested, they will definitely not be able to learn specific courses, which is undoubted, so interest is the best teacher, if you want to learn physics well, you must cultivate interest in the subject of physics.

3. Be good at observation. Physics is a discipline with strong regularity, and when you encounter the same knowledge points and the same type of questions, as long as you do it once, the next time you encounter a similar problem.

4. You won't be afraid, because you have observed the rules and mysteries in it, and you know that this is the same type of question, so you are fully capable of taking this question down, so you are not in a hurry. Because this is the type of question that has been seen, that is, a pair of observant eyes help you.

1. Energy density refers to the amount of energy stored in a certain space or mass substance.

2. The energy contained in the unit volume, unit: joule cubic meter, kilojoule cubic meter, megajoule cubic meter, dimension m(l -1) (t -2). It is used to measure the most suitable battery and compare the amount of power stored in a unit volume of battery.

The heat of gas combustion (measured by volume) is essentially the energy density.

The energy density of the electromagnetic field: 1. The energy of the magnetic field in the volume of a unit of fierce object is called the magnetic energy density. The energy stored by itself during the establishment of the magnetic field.

Abbreviated as magnetic energy. In the process of establishing a magnetic field in a coil and increasing the current from zero to a stable value, the power supply should skillfully resist the self-induced electromotive force to do the work, and the energy associated with this part of the work is called self-induced magnetic energy.

2. If the current is introduced into the two coils with mutual inductance, the power supply will not only resist the self-inductance electromotive force to do work, but also resist the mutual inductance electromotive force between the coils and do work, and the energy associated with the work of resisting the mutual inductance electric key potential is called mutual inductance magnetic energy.

A brief introduction to the energy density of the electric field is as follows:

The electric field energy density is the energy of the electric field per unit volume. The energy of the electrostatic field is an important feature of the electrostatic field, and for the energy of the electrostatic field, when the general electromagnetism textbook introduces this basic concept, the energy storage of the capacitor is used to explain the energy localization in the electric field, and the dielectric in the electric field is affected by the electric field force.

Energy in Electrostatics:

Some textbooks say that this conclusion applies to all electric fields. The electric field of the parallel-plate capacitor is only a special case among the countless electric fields, and the conclusion derived from this field is not necessarily universal, so some scholars use other methods to derive formulas to verify this conclusion. Firstly, some energy formulas in the electrostatic field are analyzed and compared, and it is pointed out that electrostatic energy is a general term for electric potential energy, self-energy or intrinsic energy, and interaction energy, and the energy of the electrostatic field is the total electrostatic energy of the charged system that excites the electrostatic field.

Derivation of electric field energy and its energy density by means of power line tubes:

Starting from the total electrostatic energy of the charged system, the electrostatic field energy of the charged system is derived, and then the energy density of the electrostatic field is obtained. A charged body with m charges continuously distributed constitutes a charged system. The charge of conductor 1 is q1 and the charge of conductor 2 is q2...

The charge of conductor m is qm. Imagine that the power lines in the electric field space are composed of an infinite number of power line tubes, and the area of each power line tube on the surface of the conductor is ds.

For the power line pipe l that is arbitrarily investigated, e·ds is a certain value, which is equal to the electric flux through the power line pipe cross-section. where E is the electric field strength of each point in the power line pipe, Ds is the cross-sectional area of the power line pipe at the point where the field strength E is located, and Ds points to the direction of the power line. For an arbitrary power line pipe L, Sj, which connects conductor J and conductor K, is in the direction of the power line, and DSK is in the opposite direction of the power line.

Using the meta-capacitance concept analysis:

The structure of the electric field can be described by using a flux tube in any free space, the number of electric flux lines in each flux tube is fixed, and the whole space is composed of infinite small dot flux halls.

It can be assumed that each flux tube is a series of countless ideal parallel plate capacitors, i.e., elemental capacitors. Since there is no free charge in space, it can be assumed that each plate of the capacitive plate in the flux tube has an equal charge on its two sides with opposite signs, so that there is no net charge in the flux tube.

Mass energy density (mj kg):; Volumetric energy density side-lift (mj l): .

The electrical energy emitted per unit volume or mass of a battery. Generally, under the same volume, the energy density of lithium-ion batteries is times that of nickel-cadmium batteries and times that of nickel-metal hydride batteries, so when the battery capacity is equal, lithium-ion batteries will be smaller and lighter than nickel-cadmium and nickel-metal hydride batteries.

Battery energy density Battery capacity Discharge platform Battery thickness Battery width Battery length.

At present, the discharge rate of conventional lithium-ion batteries is still between, and the difference in discharge capacity of general batteries during this rate period is not more than 1%. However, for high-rate discharge, the difference between the capacity and the low rate is obvious. Therefore, for batteries with special discharge rates, it is necessary to pay attention to their discharge rates and calculate the corresponding energy density.

Mobile phones basically use lithium-ion batteries. Proper use of lithium-ion batteries is important to extend battery life. It can be made into flat rectangle, cylindrical, rectangular and button type according to the requirements of different electronic products, and there is a battery pack composed of several batteries connected in series and parallel together.

The rated voltage of lithium-ion batteries, due to the change of materials, is generally the positive electrode of lithium iron phosphate (hereinafter referred to as iron phosphorus). The termination charge voltage when fully charged is generally, phosphorus iron.

The termination discharge voltage of the lithium-ion battery is given by the battery factory as the working voltage range or the termination discharge voltage is given, and the parameters are slightly different. Continuing to discharge below ferrophosphorus is called over-discharge, and over-discharge will damage the battery.