物理代写|电磁学代写electromagnetism代考|PHYC20014

statistics-lab™ 为您的留学生涯保驾护航 在代写电磁学electromagnetism方面已经树立了自己的口碑, 保证靠谱, 高质且原创的统计Statistics代写服务。我们的专家在代写电磁学electromagnetism代写方面经验极为丰富，各种代写电磁学electromagnetism相关的作业也就用不着说。

• Statistical Inference 统计推断
• Statistical Computing 统计计算
• (Generalized) Linear Models 广义线性模型
• Statistical Machine Learning 统计机器学习
• Longitudinal Data Analysis 纵向数据分析
• Foundations of Data Science 数据科学基础

物理代写|电磁学代写electromagnetism代考|Electric Field Lines

By definition, electric field lines are drawn to follow the same direction as the electric field vector at any point. Furthermore, the electric field vector is tangent to the line at every point along the field line.

The electric field lines are such that $\mathbf{E}$ is tangent to the electric field line at each point. The number of lines per unit surface area passing a surface perpendicular to the lines is proportional to the magnitude $|\mathbf{E}|$ in that region. Furthermore, the lines are directed radially away from the positive point charge. Moreover, the lines are directed radially toward the negative point charge.

In Fig. 1.7, we show the electric field lines of a negative and positive point charge. It can be seen that for a negative point charge, $-q$, the electric field lines are drawn toward the charge (see Fig. 1.7a). On the other hand, for a positive point charge, $+q$, electric field lines are leaving the charge, as shown in Fig. 1.7b.

The following general rules for drawing electric field lines apply:
The lines start from a positive charge and end on a negative charge. Also, the number of lines drawn, leaving a positive charge, or approaching a negative charge is proportional to the magnitude of the charge. Moreover, no two field lines can cross.

In Fig. 1.8, we show the electric field vector for a positive point charge $+q$ located at the point $(0,3,0)$ (Fig. 1.8b) and a negative point charge $-q$ located at $(0,-3,0)$ (Fig. 1.8a), colored according to the magnitude of the electric field $\mathbf{E}$ using a color scaling. as depicted in Fig. 1.8. Besides, the electric field lines of the resultant electric field are shown in Fig. 1.8c.

物理代写|电磁学代写electromagnetism代考|Motion in Uniform Electric Field

Suppose a charge particle of mass $m$ and charge $q$ is moving in a uniform electric field $\mathbf{E}$. Electric field $\mathbf{E}$ exerts on a particle placed in it the force
$$\mathbf{F}=q \mathbf{E}$$

If that force is equal to the resultant force exerted on the particle, it causes the particle to accelerate, based on Newton’s second law:
$$m \mathbf{a}=q \mathbf{E}$$
The acceleration gained by the charge is given as
$$\mathbf{a}=\frac{q}{m} \mathbf{E}$$
Therefore, if $\mathbf{E}$ is uniform (that is, constant in magnitude and direction), then a is constant. Furthermore, if the particle has a positive charge, then its acceleration is in the direction of the electric field. On the other hand, if the particle has a negative charge, then its acceleration is in the direction opposite the electric field.

电磁学代考

物理代写|电磁学代写electromagnetism代考|Motion in Uniform Electric Field

$$\mathbf{F}=q \mathbf{E}$$

$$m \mathbf{a}=q \mathbf{E}$$

$$\mathbf{a}=\frac{q}{m} \mathbf{E}$$

有限元方法代写

tatistics-lab作为专业的留学生服务机构，多年来已为美国、英国、加拿大、澳洲等留学热门地的学生提供专业的学术服务，包括但不限于Essay代写，Assignment代写，Dissertation代写，Report代写，小组作业代写，Proposal代写，Paper代写，Presentation代写，计算机作业代写，论文修改和润色，网课代做，exam代考等等。写作范围涵盖高中，本科，研究生等海外留学全阶段，辐射金融，经济学，会计学，审计学，管理学等全球99%专业科目。写作团队既有专业英语母语作者，也有海外名校硕博留学生，每位写作老师都拥有过硬的语言能力，专业的学科背景和学术写作经验。我们承诺100%原创，100%专业，100%准时，100%满意。

MATLAB代写

MATLAB 是一种用于技术计算的高性能语言。它将计算、可视化和编程集成在一个易于使用的环境中，其中问题和解决方案以熟悉的数学符号表示。典型用途包括：数学和计算算法开发建模、仿真和原型制作数据分析、探索和可视化科学和工程图形应用程序开发，包括图形用户界面构建MATLAB 是一个交互式系统，其基本数据元素是一个不需要维度的数组。这使您可以解决许多技术计算问题，尤其是那些具有矩阵和向量公式的问题，而只需用 C 或 Fortran 等标量非交互式语言编写程序所需的时间的一小部分。MATLAB 名称代表矩阵实验室。MATLAB 最初的编写目的是提供对由 LINPACK 和 EISPACK 项目开发的矩阵软件的轻松访问，这两个项目共同代表了矩阵计算软件的最新技术。MATLAB 经过多年的发展，得到了许多用户的投入。在大学环境中，它是数学、工程和科学入门和高级课程的标准教学工具。在工业领域，MATLAB 是高效研究、开发和分析的首选工具。MATLAB 具有一系列称为工具箱的特定于应用程序的解决方案。对于大多数 MATLAB 用户来说非常重要，工具箱允许您学习应用专业技术。工具箱是 MATLAB 函数（M 文件）的综合集合，可扩展 MATLAB 环境以解决特定类别的问题。可用工具箱的领域包括信号处理、控制系统、神经网络、模糊逻辑、小波、仿真等。

物理代写|电磁学代写electromagnetism代考|ELEC3104

statistics-lab™ 为您的留学生涯保驾护航 在代写电磁学electromagnetism方面已经树立了自己的口碑, 保证靠谱, 高质且原创的统计Statistics代写服务。我们的专家在代写电磁学electromagnetism代写方面经验极为丰富，各种代写电磁学electromagnetism相关的作业也就用不着说。

• Statistical Inference 统计推断
• Statistical Computing 统计计算
• (Generalized) Linear Models 广义线性模型
• Statistical Machine Learning 统计机器学习
• Longitudinal Data Analysis 纵向数据分析
• Foundations of Data Science 数据科学基础

物理代写|电磁学代写electromagnetism代考|Force Fields

The field forces act through space, producing an effect even when no physical contact between the objects occurs. As an example, we can mention the gravitational field. Michael Faraday developed a similar approach to electric forces. That is, an electric field exists in the region of space around any charged body, and when another charged body is inside this region of the electric field, an electric force acts on it.

Definition 1.2 The electric field $\mathbf{E}$ at a point in space is defined as the electric force $\mathbf{F}_e$ acting on a positive test charge $q_0$ placed at that point divided by the magnitude of the test charge:
$$\mathbf{E}=\frac{\mathbf{F}_e}{q_0}$$

The vector $\mathbf{E}$ has the SI units of newtons per coulomb (N/C). Figure $1.3$ illustrates the electric field $\mathbf{E}$ created by a positively charged sphere with total charge $Q$ at the positive test charge $q_0$. Here, we have assumed that the test charge $q_0$ is small enough that it does not disturb the charge distribution of the sphere responsible for the electric field.

Note that $\mathbf{E}$ is the field produced by some charge external to the test charge, and it is not the field produced by the test charge itself. Also, note that the existence of an electric field is a property of its source. For example, every electron comes with its electric field. An electric field exists at a point if a test charge at rest at that point experiences an electric force. The electric field direction is the direction of the force on a positive test charge placed in the field. Once we know the magnitude and direction of the electric field at some point, the electric force exerted on any charged particle (either positive or negative) placed at that point can be calculated. The electric field exists at some point space, including the free space, independent of the existence of another test charge at that point.

To determine the direction of electric field, consider a point charge $q$ located some distance $r$ from a test positive charge $q_0$ located at a point $P$, as shown in Fig. 1.4. Coulomb’s law defines the force exerted by $q$ on $q_0$ as
$$\mathbf{F}_e=k_e \frac{q q_0}{r^2} \hat{\mathbf{r}}$$
where $\hat{\mathbf{r}}$ represents the usual unit vector directed from $q$ toward $q_0$ (see Fig. 1.4). Electric field created by $q$ (positive or negative) is $$\mathbf{E}=\frac{\mathbf{F}_e}{q_0}=k_e \frac{q}{r^2} \hat{\mathbf{r}}$$
From Eq. (1.11), when $q<0$, then $\mathbf{E}$ is pointing opposite to vector $\hat{\mathbf{r}}$, and hence the electric field of a negative charge is pointing toward that charge, see Fig. 1.4a. On the other hand, when $q>0, \mathbf{E}$ and $\hat{\mathbf{r}}$ are parallel, and hence the electric field of a positive charge is pointing away from that charge, as shown in Fig. 1.4b.

物理代写|电磁学代写electromagnetism代考|Superposition Principle

According to superposition principle, at any point $P$, the total electric field due to a set of discrete point charges, $q_1, q_2, \ldots, q_N$, positive and negative charges, is equal to the sum of the individual charge electric field vectors (see Fig. 1.5). Mathematically, we can write
$$\mathbf{E}(\mathbf{r})=\sum_{i=1}^N \mathbf{E}i=\sum{i=1}^N k_e \frac{q_i}{\left|\mathbf{r}-\mathbf{r}_i\right|^2} \hat{\mathbf{r}}_i$$
In Eq. (1.12), $\left|\mathbf{r}-\mathbf{r}_i\right|$ is the distance from $q_i$ to the point $P$ (the location of a test charge), where $\mathbf{r}$ is the position vector of the point $P$ with respect to some reference frame, as indicated in Fig. 1.5, and $\mathbf{r}_i$ is the position vector of the charge $i$ in that reference frame. Furthermore, $\hat{\mathbf{r}}_i$ is a unit vector directed from $q_i$ toward $P$.

Note that in Eq. (1.12) the dependence of $\mathbf{E}$ on only position vector of point $P$. r. assumes a static configuration of the charges in space. That is, for some other configuration distribution of charges in space, $\mathbf{E}$ at the same point $P$ may be different. Note that often for convenience, Eq.(1.12) is also written as $$\mathbf{E}(\mathbf{r})=\sum_{i=1}^N k_e \frac{q_i\left(\mathbf{r}-\mathbf{r}_i\right)}{\left|\mathbf{r}-\mathbf{r}_i\right|^3}$$
where
$$\hat{\mathbf{r}}_i=\frac{\mathbf{r}-\mathbf{r}_i}{\left|\mathbf{r}-\mathbf{r}_i\right|}$$
If the distances between charges in a set of charges are much smaller, compare with the distance of the set from a point where the electric field is to be calculated, then charge distribution is continuous.

To calculate the net electric field created by a continuous charge distribution in some volume $V$, we follow these steps. First, we divide the charge distribution into macroscopically small elements with small charge $\Delta q_i$, as shown in Fig. 1.6a. $\Delta q_i=\rho_i \Delta V$, where $\rho_i$ is seen from a microscopic viewpoint as a uniform charge density within the volume element $i$, which represents one of the possible configurations of microscopic description. It is important to note that with “macroscopically small” we should understand a small volume in space with a characteristic microscopic configuration of the charges inside it that can, on average, macroscopically be represented as a point-like charge, $\Delta q_i$. Then, we calculate the electric field due to one of these macroscopically point charges, $\Delta q_i$, at some point $P$ at distance $\left|\mathbf{r}-\mathbf{r}_i\right|$ from the charge element, $\Delta q_i$, as
$$\Delta \mathbf{E}\left(\mathbf{r}, \mathbf{r}_i\right)=k_e \frac{\Delta q_i}{\left|\mathbf{r}-\mathbf{r}_i\right|^2} \hat{\mathbf{r}}_i$$
where $\hat{\mathbf{r}}_i$ is a unit vector directed from the charge element $\Delta q_i$ toward $P$. Here, $\mathbf{r}$ is position vector of point $P$ in some reference frame, and $\mathbf{r}_i$ is the position vector of the macroscopically point charge $\Delta q_i$.

电磁学代考

物理代写|电磁学代写electromagnetism代考|Force Fields

$$\mathbf{E}=\frac{\mathbf{F}_e}{q_0}$$

$$\mathbf{F}_e=k_e \frac{q q_0}{r^2} \hat{\mathbf{r}}$$

$$\mathbf{E}=\frac{\mathbf{F}_e}{q_0}=k_e \frac{q}{r^2} \hat{\mathbf{r}}$$

物理代写|电磁学代写electromagnetism代考|Superposition Principle

$$\mathbf{E}(\mathbf{r})=\sum_{i=1}^N \mathbf{E} i=\sum i=1^N k_e \frac{q_i}{\left|\mathbf{r}-\mathbf{r}i\right|^2} \hat{\mathbf{r}}_i$$ 在等式中。(1.12)， $\left|\mathbf{r}-\mathbf{r}_i\right|$ 是距离 $q_i$ 直截了当 $P$ (测试电荷的位置)，其中 $\mathbf{r}$ 是点的位置向量 $P$ 关于一些 参考系，如图 1.5 所示，以及 $\mathbf{r}_i$ 是电荷的位置向量 $i$ 在那个参考系中。此外， $\hat{\mathbf{r}}_i$ 是指向的单位向量 $q_i$ 朝向 $P$. 请注意，在等式中。(1.12) 的依赖 $\mathbf{E}$ 仅在点的位置向量上 $P$. 河 假定空间中电荷的静态配置。也就是说， 对于空间中电荷的一些其他配置分布， $\mathbf{E}$ 在同一时间 $P$ 可能不同。请注意，通常为方便起见，Eq.(1.12) 也写为 $$\mathbf{E}(\mathbf{r})=\sum{i=1}^N k_e \frac{q_i\left(\mathbf{r}-\mathbf{r}_i\right)}{\left|\mathbf{r}-\mathbf{r}_i\right|^3}$$

$$\hat{\mathbf{r}}_i=\frac{\mathbf{r}-\mathbf{r}_i}{\left|\mathbf{r}-\mathbf{r}_i\right|}$$

$$\Delta \mathbf{E}\left(\mathbf{r}, \mathbf{r}_i\right)=k_e \frac{\Delta q_i}{\left|\mathbf{r}-\mathbf{r}_i\right|^2} \hat{\mathbf{r}}_i$$

有限元方法代写

tatistics-lab作为专业的留学生服务机构，多年来已为美国、英国、加拿大、澳洲等留学热门地的学生提供专业的学术服务，包括但不限于Essay代写，Assignment代写，Dissertation代写，Report代写，小组作业代写，Proposal代写，Paper代写，Presentation代写，计算机作业代写，论文修改和润色，网课代做，exam代考等等。写作范围涵盖高中，本科，研究生等海外留学全阶段，辐射金融，经济学，会计学，审计学，管理学等全球99%专业科目。写作团队既有专业英语母语作者，也有海外名校硕博留学生，每位写作老师都拥有过硬的语言能力，专业的学科背景和学术写作经验。我们承诺100%原创，100%专业，100%准时，100%满意。

MATLAB代写

MATLAB 是一种用于技术计算的高性能语言。它将计算、可视化和编程集成在一个易于使用的环境中，其中问题和解决方案以熟悉的数学符号表示。典型用途包括：数学和计算算法开发建模、仿真和原型制作数据分析、探索和可视化科学和工程图形应用程序开发，包括图形用户界面构建MATLAB 是一个交互式系统，其基本数据元素是一个不需要维度的数组。这使您可以解决许多技术计算问题，尤其是那些具有矩阵和向量公式的问题，而只需用 C 或 Fortran 等标量非交互式语言编写程序所需的时间的一小部分。MATLAB 名称代表矩阵实验室。MATLAB 最初的编写目的是提供对由 LINPACK 和 EISPACK 项目开发的矩阵软件的轻松访问，这两个项目共同代表了矩阵计算软件的最新技术。MATLAB 经过多年的发展，得到了许多用户的投入。在大学环境中，它是数学、工程和科学入门和高级课程的标准教学工具。在工业领域，MATLAB 是高效研究、开发和分析的首选工具。MATLAB 具有一系列称为工具箱的特定于应用程序的解决方案。对于大多数 MATLAB 用户来说非常重要，工具箱允许您学习应用专业技术。工具箱是 MATLAB 函数（M 文件）的综合集合，可扩展 MATLAB 环境以解决特定类别的问题。可用工具箱的领域包括信号处理、控制系统、神经网络、模糊逻辑、小波、仿真等。

物理代写|电磁学代写electromagnetism代考|PHYS3040

statistics-lab™ 为您的留学生涯保驾护航 在代写电磁学electromagnetism方面已经树立了自己的口碑, 保证靠谱, 高质且原创的统计Statistics代写服务。我们的专家在代写电磁学electromagnetism代写方面经验极为丰富，各种代写电磁学electromagnetism相关的作业也就用不着说。

• Statistical Inference 统计推断
• Statistical Computing 统计计算
• (Generalized) Linear Models 广义线性模型
• Statistical Machine Learning 统计机器学习
• Longitudinal Data Analysis 纵向数据分析
• Foundations of Data Science 数据科学基础

物理代写|电磁学代写electromagnetism代考|Electrical Charges

There exist several simple experiments to demonstrate the existence of electrical charges and forces. For example,

1. When we comb our hair on a dry day, we find that the comb attracts pieces of paper.
2. The same effect of attracting pieces of paper occurs when materials such as glass or rubber are rubbed with silk or fur.

As a general rule, for every material behaving in that way, we can say that it is electrified, or it becomes electrically charged.

Benjamin Franklin (1706-1790) found that there exist two types of electric charges, namely positive and negative. The following experiment can be used to demonstrate his finding. Suppose that we rubber with fur a hard rubber rod. In addition, we rub a glass rod with silk material. Then, if the glass rod is brought near the rubber rod, we will observe that the two attract each other. However, if we bring near each other two charged rubber rods or two charged glass rods, then the two repel each other. This experiment indicates the existence of two different states of electrification for the rubber and glass. Furthermore, it finds that like charges repel each other and unlike charges attract each other.

By convention, the electric charge on the glass rod is positive, and that on the rubber rod is negative. Based on that convention, any charged object repelled by another charged object must have the same sign of charge with it, and any charged object attracted by another charged object must have an opposite sign of charge. It is important to note that the electricity model of Franklin implies that electric charge is always conserved. That is, an electrified state (positive or negative) is due to the charge transfer from one object to the other. In other words, when an object gains some amount of positive/negative charge, then the other gains an equal amount of the electric charge of the opposite sign.

Robert Millikan (1868-1953), in 1909, discovered that electric charge always appears as a multiple integer of a fundamental amount of charge, called $e$ such that the electric charge $q$, which is a standard symbol for the charge, is quantized as
$$q=N e$$
Here, $N$ is an integer number, $N=0, \pm 1, \pm 2, \ldots$.

物理代写|电磁学代写electromagnetism代考|Coulomb’s Law

Based on an experiment performed by Coulomb, the electric force between two charged particles at rest is proportional to the inverse of the square of distance $r$ between them and directed along the line joining the two particles. In addition, the electric force is proportional to the charges $q_1$ and $q_2$ on each particle. Also, the electric force is attractive if the charges are of opposite sign and repulsive if the charges have the same sign. That is known as Coulomb’s Law.

Definition 1.1 Force is proportional to the product of the magnitudes of the charges and inversely proportional to the square of the distance between them. Mathematically, the law may be written as
$$F=k_e \frac{\left|q_1\right|\left|q_2\right|}{r^2}$$
In Eq. (1.2), $k_e$ is the Coulomb constant. Note that, in SI, the unit of charge is the coulomb (C). Therefore, the Coulomb constant $k_e$ in SI units has the value
$$k_e=8.9875 \times 10^9 \mathrm{~N} \cdot \mathrm{m}^2 / \mathrm{C}^2$$
Often, the constant is written as $$k_e=\frac{1}{4 \pi \epsilon_0}$$
where $\epsilon_0$ is the permittivity of free space given by
$$\epsilon_0=8.8542 \times 10^{-12} \mathrm{C}^2 / \mathrm{N} \cdot \mathrm{m}^2$$
Coulomb’s force is a vector; hence it has a magnitude expressed by Eq. (1.2) and a direction. Therefore, the Coulomb’s law can be expressed in vector form concerning the electric force, $\mathbf{F}{12}$, exerted by the charge $q_1$ (positive or negative) on another charge $q_2$ (positive or negative) as $$\mathbf{F}{12}=k_e \frac{q_1 q_2}{r^2} \hat{\mathbf{r}}$$
In Eq. (1.6), $\hat{\mathbf{r}}$ denotes a unit vector pointing from $q_1$ to $q_2$. Note that based on the Newton’s third law, the electric force, $\mathbf{F}{21}$, exerted by a charge $q_2$ (positive or negative) on a second charge $q_2$ (positive or negative) is $$\mathbf{F}{21}=-\mathbf{F}_{12}$$
Figure $1.1$ illustrates graphically the direction of Coulomb’s force vectors for different combinations of the pairs of positive and negative charges, namely negativenegative, positive-positive, and negative-positive charge-charge interactions.

电磁学代考

物理代写|电磁学代写electromagnetism代考|Electrical Charges

1. 当我们在干燥的日子㓍头时，我们发现㓍子会吸引纸片。
2. 当玻璃或橡胶等材料与丝绸或毛皮摩擦时，也会产生吸引纸片的相同效果。
作为一般规则，对于以这种方式表现的每种材料，我们可以说它带电，或者带电。
本杰明·富兰克林 (1706-1790) 发现存在两种电荷，即正电荷和负电荷。下面的实验可以用来证明他的 发现。假设我们用毛皮橡胶一根硬橡胶棒。此外，我们用丝绸材料摩擦玻璃棒。然后，如果将玻璃棒靠 近橡胶棒，我们会观察到两者相互吸引。但是，如果我们将两根带电的橡胶棒或两根带电的玻璃棒靠 近，那么两者就会相互排斥。该实验表明橡胶和玻璃存在两种不同的带电状态。此外，它发现同种电荷 相互排斥，不同种电荷相互吸引。
按照惯例，玻璃棒上的电荷为正，橡胶棒上的电荷为负。根据该约定，任何被另一个带电物体排斥的带 电物体必须具有与其相同的电荷符号，而任何被另一个带电物体吸引的带电物体必须具有相反的电荷符 号。重要的是要注意富兰克林的电模型意味着电荷总是守恒的。也就是说，带电状态 (正或负) 是由于 电荷从一个物体转移到另一个物体。换句话说，当一个物体获得一定量的正/负电荷时，另一个物体获得 等量的相反符号的电荷。

Robert Millikan (1868-1953) 在 1909 年发现电荷总是以基本电荷量的整数倍形式出现，称为 $e$ 这样电荷 $q$ ，这是电荷的标准符号，被量化为
$$q=N e$$

物理代写|电磁学代写electromagnetism代考|Coulomb’s Law

$$F=k_e \frac{\left|q_1\right|\left|q_2\right|}{r^2}$$

$$k_e=8.9875 \times 10^9 \mathrm{~N} \cdot \mathrm{m}^2 / \mathrm{C}^2$$

$$k_e=\frac{1}{4 \pi \epsilon_0}$$

$$\epsilon_0=8.8542 \times 10^{-12} \mathrm{C}^2 / \mathrm{N} \cdot \mathrm{m}^2$$

$$\mathbf{F} 12=k_e \frac{q_1 q_2}{r^2} \hat{\mathbf{r}}$$

$$\mathbf{F} 21=-\mathbf{F}_{12}$$

有限元方法代写

tatistics-lab作为专业的留学生服务机构，多年来已为美国、英国、加拿大、澳洲等留学热门地的学生提供专业的学术服务，包括但不限于Essay代写，Assignment代写，Dissertation代写，Report代写，小组作业代写，Proposal代写，Paper代写，Presentation代写，计算机作业代写，论文修改和润色，网课代做，exam代考等等。写作范围涵盖高中，本科，研究生等海外留学全阶段，辐射金融，经济学，会计学，审计学，管理学等全球99%专业科目。写作团队既有专业英语母语作者，也有海外名校硕博留学生，每位写作老师都拥有过硬的语言能力，专业的学科背景和学术写作经验。我们承诺100%原创，100%专业，100%准时，100%满意。

MATLAB代写

MATLAB 是一种用于技术计算的高性能语言。它将计算、可视化和编程集成在一个易于使用的环境中，其中问题和解决方案以熟悉的数学符号表示。典型用途包括：数学和计算算法开发建模、仿真和原型制作数据分析、探索和可视化科学和工程图形应用程序开发，包括图形用户界面构建MATLAB 是一个交互式系统，其基本数据元素是一个不需要维度的数组。这使您可以解决许多技术计算问题，尤其是那些具有矩阵和向量公式的问题，而只需用 C 或 Fortran 等标量非交互式语言编写程序所需的时间的一小部分。MATLAB 名称代表矩阵实验室。MATLAB 最初的编写目的是提供对由 LINPACK 和 EISPACK 项目开发的矩阵软件的轻松访问，这两个项目共同代表了矩阵计算软件的最新技术。MATLAB 经过多年的发展，得到了许多用户的投入。在大学环境中，它是数学、工程和科学入门和高级课程的标准教学工具。在工业领域，MATLAB 是高效研究、开发和分析的首选工具。MATLAB 具有一系列称为工具箱的特定于应用程序的解决方案。对于大多数 MATLAB 用户来说非常重要，工具箱允许您学习应用专业技术。工具箱是 MATLAB 函数（M 文件）的综合集合，可扩展 MATLAB 环境以解决特定类别的问题。可用工具箱的领域包括信号处理、控制系统、神经网络、模糊逻辑、小波、仿真等。

物理代写|电磁学代写electromagnetism代考|ELEC3104

statistics-lab™ 为您的留学生涯保驾护航 在代写电磁学electromagnetism方面已经树立了自己的口碑, 保证靠谱, 高质且原创的统计Statistics代写服务。我们的专家在代写电磁学electromagnetism代写方面经验极为丰富，各种代写电磁学electromagnetism相关的作业也就用不着说。

• Statistical Inference 统计推断
• Statistical Computing 统计计算
• (Generalized) Linear Models 广义线性模型
• Statistical Machine Learning 统计机器学习
• Longitudinal Data Analysis 纵向数据分析
• Foundations of Data Science 数据科学基础

物理代写|电磁学代写electromagnetism代考|Electric Current

Consider the motion in a system of electric charges, as presented in Fig.5.1. A current will exist, if there is a net flow of charge through a region. To define current, we consider the charges moving as in Fig. $5.1$ and a surface of area $A$ perpendicular to the direction of motion of the charges.

By definition, the ratio of the amount of charge $\Delta Q$ that passes through the surface area $A$ in a time interval $\Delta t$ is the average current $I_{a v}$ :
$$I_{a v}=\frac{\Delta Q}{\Delta t}$$
which represents the charge that passes through $A$ per unit time. If the charge flow rate, $\Delta Q / \Delta t$ varies in time, then the current varies in time.

Then, the instantaneous current $I$ is define as
$$I=\lim _{\Delta t \rightarrow 0} \frac{\Delta Q}{\Delta t}=\frac{d Q}{d t}$$
Note that the instantaneous current $I$ is simply called electric current or current. In the SI units, the current has a unit of the ampere (A):
$$1 \mathrm{~A}=1 \frac{\mathrm{C}}{\mathrm{s}}$$
Equation (5.2) implies that a current of $1 \mathrm{~A}$ is equivalent to a charge of $1 \mathrm{C}$ passing through the surface area in $1 \mathrm{~s}$.

物理代写|电磁学代写electromagnetism代考|Microscopic Model of Current

In the following, we describe a microscopic model of conduction in a conductor to relate the current to the motion of the charge carriers. In particular, we will consider the current in a conductor with a cross-sectional area $A$, as shown in Fig. 5.3. Consider a section of the conductor with a length $\Delta x$. The volume of that section is
$$\Delta V=A \Delta x=A v_d \Delta t$$
Suppose that $n$ is the volume number density of mobile charge carriers (or the charge carrier density), then, the total number of carriers in the volume $\Delta V$ is
$$N=n A \Delta x=n A v_d \Delta t$$

Therefore, the charge $\Delta Q$ in this volume is
$$\Delta Q=N q=q n A \Delta x=q n A v_d \Delta t$$
From Eq. (5.1), the average current in the conductor is
$$I_{a v}=\frac{\Delta Q}{\Delta t}=q n A v_d$$
By definition, the drift speed represents the average speed of the charge carriers, denoted as $v_d$. To understand the drift speed, we will consider a conductor, and hence the charge carriers are free electrons. For an isolated conductor, the potential difference across it is zero, as described above for Fig. $5.3$, thus these electrons move randomly as the motion of molecules of the gas in a container. If we apply a potential difference across the conductor utilizing a battery, as also described above in Fig. 5.4, an electric field sets up in the conductor. That field exerts an electric force on the electrons, accelerating them in a given direction. That directed movement of electrons produces a current, as shown in Fig. 5.4. It is important to note that the electrons do not move in straight lines along the conductor. Indeed, they collide regularly with the atoms of the conductor, and hence their resultant motion is a complicated movement, considered here as a spiral motion. However, the collision just slows down the motion, because the electrons move slowly along the conductor (in a direction opposite to $\mathbf{E}$ ) with a drift velocity $\mathbf{v}_d$, as shown in Fig. 5.4.

电磁学代考

物理代写|电磁学代写electromagnetism代考|Electric Current

$$I_{a v}=\frac{\Delta Q}{\Delta t}$$

$$I=\lim _{\Delta t \rightarrow 0} \frac{\Delta Q}{\Delta t}=\frac{d Q}{d t}$$

$$1 \mathrm{~A}=1 \frac{\mathrm{C}}{\mathrm{s}}$$

物理代写|电磁学代写electromagnetism代考|Microscopic Model of Current

$$\Delta V=A \Delta x=A v_d \Delta t$$

$$N=n A \Delta x=n A v_d \Delta t$$

$$\Delta Q=N q=q n A \Delta x=q n A v_d \Delta t$$

$$I_{a v}=\frac{\Delta Q}{\Delta t}=q n A v_d$$

有限元方法代写

tatistics-lab作为专业的留学生服务机构，多年来已为美国、英国、加拿大、澳洲等留学热门地的学生提供专业的学术服务，包括但不限于Essay代写，Assignment代写，Dissertation代写，Report代写，小组作业代写，Proposal代写，Paper代写，Presentation代写，计算机作业代写，论文修改和润色，网课代做，exam代考等等。写作范围涵盖高中，本科，研究生等海外留学全阶段，辐射金融，经济学，会计学，审计学，管理学等全球99%专业科目。写作团队既有专业英语母语作者，也有海外名校硕博留学生，每位写作老师都拥有过硬的语言能力，专业的学科背景和学术写作经验。我们承诺100%原创，100%专业，100%准时，100%满意。

MATLAB代写

MATLAB 是一种用于技术计算的高性能语言。它将计算、可视化和编程集成在一个易于使用的环境中，其中问题和解决方案以熟悉的数学符号表示。典型用途包括：数学和计算算法开发建模、仿真和原型制作数据分析、探索和可视化科学和工程图形应用程序开发，包括图形用户界面构建MATLAB 是一个交互式系统，其基本数据元素是一个不需要维度的数组。这使您可以解决许多技术计算问题，尤其是那些具有矩阵和向量公式的问题，而只需用 C 或 Fortran 等标量非交互式语言编写程序所需的时间的一小部分。MATLAB 名称代表矩阵实验室。MATLAB 最初的编写目的是提供对由 LINPACK 和 EISPACK 项目开发的矩阵软件的轻松访问，这两个项目共同代表了矩阵计算软件的最新技术。MATLAB 经过多年的发展，得到了许多用户的投入。在大学环境中，它是数学、工程和科学入门和高级课程的标准教学工具。在工业领域，MATLAB 是高效研究、开发和分析的首选工具。MATLAB 具有一系列称为工具箱的特定于应用程序的解决方案。对于大多数 MATLAB 用户来说非常重要，工具箱允许您学习应用专业技术。工具箱是 MATLAB 函数（M 文件）的综合集合，可扩展 MATLAB 环境以解决特定类别的问题。可用工具箱的领域包括信号处理、控制系统、神经网络、模糊逻辑、小波、仿真等。

物理代写|电磁学代写electromagnetism代考|PHYC20014

statistics-lab™ 为您的留学生涯保驾护航 在代写电磁学electromagnetism方面已经树立了自己的口碑, 保证靠谱, 高质且原创的统计Statistics代写服务。我们的专家在代写电磁学electromagnetism代写方面经验极为丰富，各种代写电磁学electromagnetism相关的作业也就用不着说。

• Statistical Inference 统计推断
• Statistical Computing 统计计算
• (Generalized) Linear Models 广义线性模型
• Statistical Machine Learning 统计机器学习
• Longitudinal Data Analysis 纵向数据分析
• Foundations of Data Science 数据科学基础

物理代写|电磁学代写electromagnetism代考|Maxwell Equations for Dielectric Media Electrostatic

We mentioned that in the dielectric medium, an average over macroscopically small volumes, which are microscopically large, is necessary to obtain the Maxwell equations of the macroscopic phenomena.
The first observation is that Eq. (4.74) holds microscopically, that is
$$\nabla \times \mathbf{E}_{\text {micro }}=0$$
When averaging is made of the homogeneous Eq. (4.75), we obtain
$$\nabla \times \mathbf{E}=0$$
Equation (4.76) indicates that Eq. (4.74) holds for the averaged macroscopic electric field $\mathbf{E}$.

Using Eq. (4.57) for the effective charge density in the medium, Eq. (4.69) becomes
$$\nabla \cdot \mathbf{E}(\mathbf{r})=\frac{\rho(\mathbf{r})-\nabla \cdot \mathbf{P}(\mathbf{r})}{\epsilon_0}$$
Rearranging Eq. (4.77), we get
$$\nabla \cdot\left(\epsilon_0 \mathbf{E}(\mathbf{r})+\mathbf{P}(\mathbf{r})\right)=\rho(\mathbf{r})$$
Using the definition of the electric displacement vector given by Eq. (4.58), we write Eq. (4.78) as
$$\nabla \cdot \mathbf{D}(\mathbf{r})=\rho(\mathbf{r})$$
Note that Eqs. (4.76) and (4.79) are the macroscopic Maxwell equations in the dielectric medium, which are the counterparts of Eqs. (4.69) and (4.74).

物理代写|电磁学代写electromagnetism代考|Potential Energy of Electrostatic Field

Often, it is practical to interpret the electrostatic potential energy that emphasizes the interactions between the charges of a system as the energy stored in the electric field surrounding the charges. In that way, we emphasize the electric field instead of electric potential.

For that, we can use Eq. (3.41) (Chap. 3), and the first Maxwell’s equation in the free space as $\rho=\epsilon_0(\nabla \cdot \mathbf{E})$, then we write:

$$U=\frac{1}{2} \int_V \mathrm{~F}_0(\mathrm{~V} \cdot \mathbf{E}) \phi(\mathbf{r}) d \mathbf{r}$$
Furthermore, using Eq. (3.44) (Chap. 3), we obtain
$$U=-\frac{\epsilon_0}{2} \int_V\left(\nabla^2 \phi(\mathbf{r})\right) \phi(\mathbf{r}) d \mathbf{r}$$
If we integrate by parts in Eq. (4.81), we get
$$U=\frac{\epsilon_0}{2} \int_V(\nabla \phi(\mathbf{r}))^2 d \mathbf{r}=\frac{\epsilon_0}{2} \int_V|\mathbf{E}|^2 d \mathbf{r}$$
The integrand in Eq. (4.82) can be identified as the energy density, $u$ :
$$u=\frac{\epsilon_0}{2}|\mathbf{E}|^2$$
It is worth noting that the form of the right-hand side of Eq. (4.83) implies that $u \geq$ 0 ; therefore, the total electrostatic potential energy $U \geq 0$. However, the electrostatic potential of the system of two charges discussed in Chap. 3 (see Eq. (3.28)) implies that when the two charges have opposite sign, then electrostatic potential, $U$, is negative. The reason for that contradiction is that the expression of $U$ given by Eqs. (4.82) and (4.83) includes the self-energy term to the energy density; while Eq. (3.28), or more general Eq. (3.29), given in Chap.3, does not.

电磁学代考

物理代写|电磁学代写electromagnetism代考|Maxwell Equations for Dielectric Media Electrostatic

$$\nabla \times \mathbf{E}_{\text {micro }}=0$$

$$\nabla \times \mathbf{E}=0$$

$$\nabla \cdot \mathbf{E}(\mathbf{r})=\frac{\rho(\mathbf{r})-\nabla \cdot \mathbf{P}(\mathbf{r})}{\epsilon_0}$$

$$\nabla \cdot\left(\epsilon_0 \mathbf{E}(\mathbf{r})+\mathbf{P}(\mathbf{r})\right)=\rho(\mathbf{r})$$

$$\nabla \cdot \mathbf{D}(\mathbf{r})=\rho(\mathbf{r})$$

物理代写|电磁学代写electromagnetism代考|Potential Energy of Electrostatic Field

$$U=\frac{1}{2} \int_V \mathrm{~F}_0(\mathrm{~V} \cdot \mathbf{E}) \phi(\mathbf{r}) d \mathbf{r}$$

$$U=-\frac{\epsilon_0}{2} \int_V\left(\nabla^2 \phi(\mathbf{r})\right) \phi(\mathbf{r}) d \mathbf{r}$$

$$U=\frac{\epsilon_0}{2} \int_V(\nabla \phi(\mathbf{r}))^2 d \mathbf{r}=\frac{\epsilon_0}{2} \int_V|\mathbf{E}|^2 d \mathbf{r}$$

$$u=\frac{\epsilon_0}{2}|\mathbf{E}|^2$$

有限元方法代写

tatistics-lab作为专业的留学生服务机构，多年来已为美国、英国、加拿大、澳洲等留学热门地的学生提供专业的学术服务，包括但不限于Essay代写，Assignment代写，Dissertation代写，Report代写，小组作业代写，Proposal代写，Paper代写，Presentation代写，计算机作业代写，论文修改和润色，网课代做，exam代考等等。写作范围涵盖高中，本科，研究生等海外留学全阶段，辐射金融，经济学，会计学，审计学，管理学等全球99%专业科目。写作团队既有专业英语母语作者，也有海外名校硕博留学生，每位写作老师都拥有过硬的语言能力，专业的学科背景和学术写作经验。我们承诺100%原创，100%专业，100%准时，100%满意。

MATLAB代写

MATLAB 是一种用于技术计算的高性能语言。它将计算、可视化和编程集成在一个易于使用的环境中，其中问题和解决方案以熟悉的数学符号表示。典型用途包括：数学和计算算法开发建模、仿真和原型制作数据分析、探索和可视化科学和工程图形应用程序开发，包括图形用户界面构建MATLAB 是一个交互式系统，其基本数据元素是一个不需要维度的数组。这使您可以解决许多技术计算问题，尤其是那些具有矩阵和向量公式的问题，而只需用 C 或 Fortran 等标量非交互式语言编写程序所需的时间的一小部分。MATLAB 名称代表矩阵实验室。MATLAB 最初的编写目的是提供对由 LINPACK 和 EISPACK 项目开发的矩阵软件的轻松访问，这两个项目共同代表了矩阵计算软件的最新技术。MATLAB 经过多年的发展，得到了许多用户的投入。在大学环境中，它是数学、工程和科学入门和高级课程的标准教学工具。在工业领域，MATLAB 是高效研究、开发和分析的首选工具。MATLAB 具有一系列称为工具箱的特定于应用程序的解决方案。对于大多数 MATLAB 用户来说非常重要，工具箱允许您学习应用专业技术。工具箱是 MATLAB 函数（M 文件）的综合集合，可扩展 MATLAB 环境以解决特定类别的问题。可用工具箱的领域包括信号处理、控制系统、神经网络、模糊逻辑、小波、仿真等。

物理代写|电磁学代写electromagnetism代考|PHYS3040

statistics-lab™ 为您的留学生涯保驾护航 在代写电磁学electromagnetism方面已经树立了自己的口碑, 保证靠谱, 高质且原创的统计Statistics代写服务。我们的专家在代写电磁学electromagnetism代写方面经验极为丰富，各种代写电磁学electromagnetism相关的作业也就用不着说。

• Statistical Inference 统计推断
• Statistical Computing 统计计算
• (Generalized) Linear Models 广义线性模型
• Statistical Machine Learning 统计机器学习
• Longitudinal Data Analysis 纵向数据分析
• Foundations of Data Science 数据科学基础

物理代写|电磁学代写electromagnetism代考|Electric Polarization

Consider an electric field applied to a medium made up of a large number of particles, such as atoms or molecules. The charges bound in molecules will then respond to the external electric field, and they will follow the perturbed motion to align with the external field. Thus, the charge density within the molecules will be distorted. The dipole moments ${ }^3$ of each molecule will be different in comparison to the dipole moments in the absence of the applied electric field. That is, in the absence of the external field, the average dipole moments over all molecules of the substance are zero because the dipole vectors are oriented randomly. In contrast, in the presence of the applied electric field, the net dipole moment of the substance is different from zero. Therefore, in the medium, there is an average dipole moment per unit volume, which is called electric polarization $\mathbf{P}$, given as
$$\mathbf{P}(\mathbf{r})=\sum_i n_i\left\langle\mathbf{p}_i\right\rangle$$
In Eq. (4.51), $\mathbf{p}_i$ is the dipole moment of the molecule type $i$ in the medium, $\langle\cdots\rangle$ denotes the average over a small volume around $\mathbf{r}$, and $n_i$ is the average number per unit volume of the molecule type $i$ at the position $\mathbf{r}$.

If the net charge of the molecule $i$ is $Q_i$, and there is a macroscopic excess or free charge, the charge density at the macroscopic level is
$$\rho(\mathbf{r})=\sum_i n_i\left\langle Q_i\right\rangle+\rho_{\text {free }}$$
Note that, in general, average charge of a molecule $i$ is zero, $\left\langle Q_i\right\rangle=0$, and hence, the charge density $\rho$ is equal to the macroscopic excess or free charge, $\rho_{\text {free }}$.

In the following, we will consider the case of a continuous charge distribution, as in Fig. 3.6 (Chap. 3), and see the medium from a macroscopic viewpoint. The potential at some point $P$ at the position $\mathbf{r}$ from a macroscopic small volume element $d V$ at the position $\mathbf{r}^{\prime}$ is the sum of the potential created by the charge of $d V, d q=\rho\left(\mathbf{r}^{\prime}\right) d V$ and the dipole moment of $d V$ is $\mathbf{P}\left(\mathbf{r}^{\prime}\right) d V$, assuming that there are no higher macroscopic multipole moment densities:
$$d \phi\left(\mathbf{r}, \mathbf{r}^{\prime}\right)=k_e\left(\frac{\rho\left(\mathbf{r}^{\prime}\right) d V}{\left|\mathbf{r}-\mathbf{r}^{\prime}\right|}+\frac{\mathbf{P}\left(\mathbf{r}^{\prime}\right) \cdot\left(\mathbf{r}-\mathbf{r}^{\prime}\right) d V}{\left|\mathbf{r}-\mathbf{r}^{\prime}\right|^3}\right)$$
In Eq. (4.53), $P$ is outside the volume $d V$. To obtain the electric potential, we integrate over all space by treating the element volume $d V$ as macroscopically infinitesimal, and hence $d V=d \mathbf{r}^{\prime}$ .

First, we introduce the set of Maxwell equations for the electrostatic field in free space. Using Gauss’s Law (see Chap.2), we can write the electric flux of electric field created by continuous charge distribution in a volume $V$ enclosed by the surface $A$ as
$$\oint_A \mathbf{E} \cdot d \mathbf{A}=\frac{Q_{i n}}{\epsilon_0}$$
Note that in Eq. (4.65) $\mathbf{E}$ is the electrostatic field created by all charges in space, and $Q_{i n}$ is the electric charge inside the volume $V$ enclosed by the surface $A$. The left-hand side of Eq. (4.65) can be written in the following form using Gauss formula:

$$\oint_A \mathbf{E} \cdot d \mathbf{A}=\int_V \nabla \cdot \mathbf{E} d V$$
where $V$ is the volume enclosed by the surface $A$. In addition, the right-hand side of Eq. (4.65) can be written as
$$\frac{Q_{i n}}{\epsilon_0}=\int_V \frac{\rho(\mathbf{r})}{\epsilon_0} d V$$
Combining Eqs. (4.65), (4.66) and (4.67), we get
$$\int_V \nabla \cdot \mathbf{E} d V=\int_V \frac{\rho(\mathbf{r})}{\epsilon_0} d V$$
where $\nabla \cdot \mathbf{E}$ is the divergence of the vector $\mathbf{E}$, which produces a scalar.
Comparing both sides of Eq. (4.68), we obtain the first Maxwell equation in free space:
$$\nabla \cdot \mathbf{E}(\mathbf{r})=\frac{\rho(\mathbf{r})}{\epsilon_0}$$
where both $\mathbf{E}$ and $\rho$ can be functions of the position $\mathbf{r}$.
Using the expression of the electrostatic potential difference in free space, Eq. (4.10) (Chap.3), we have
$$\Delta \phi=-\int_A^B \mathbf{E} \cdot d \mathbf{s}$$
where $A$ and $B$ are two points in free space, and $d \mathbf{s}$ is an infinitesimal displacement along the curve joining points $A$ and $B$.

电磁学代考

物理代写|电磁学代写electromagnetism代考|Electric Polarization

$$\mathbf{P}(\mathbf{r})=\sum_i n_i\left\langle\mathbf{p}i\right\rangle$$ 在等式中。(4.51), $\mathbf{p}_i$ 是分子类型的偶极矩 $i$ 在媒体中， $\langle\cdots\rangle$ 表示周围小体积的平均值 $\mathbf{r}$ ，和 $n_i$ 是分子类型 每单位体积的平均数 $i$ 在那个位置r. 如果分子的净电荷 $i$ 是 $Q_i$ ，并且存在宏观过剩或自由电荷，宏观层面的电荷密度为 $$\rho(\mathbf{r})=\sum_i n_i\left\langle Q_i\right\rangle+\rho{\text {free }}$$

$$d \phi\left(\mathbf{r}, \mathbf{r}^{\prime}\right)=k_e\left(\frac{\rho\left(\mathbf{r}^{\prime}\right) d V}{\left|\mathbf{r}-\mathbf{r}^{\prime}\right|}+\frac{\mathbf{P}\left(\mathbf{r}^{\prime}\right) \cdot\left(\mathbf{r}-\mathbf{r}^{\prime}\right) d V}{\left|\mathbf{r}-\mathbf{r}^{\prime}\right|^3}\right)$$

$$\oint_A \mathbf{E} \cdot d \mathbf{A}=\frac{Q_{i n}}{\epsilon_0}$$

$$\oint_A \mathbf{E} \cdot d \mathbf{A}=\int_V \nabla \cdot \mathbf{E} d V$$

$$\frac{Q_{i n}}{\epsilon_0}=\int_V \frac{\rho(\mathbf{r})}{\epsilon_0} d V$$

$$\int_V \nabla \cdot \mathbf{E} d V=\int_V \frac{\rho(\mathbf{r})}{\epsilon_0} d V$$

$$\nabla \cdot \mathbf{E}(\mathbf{r})=\frac{\rho(\mathbf{r})}{\epsilon_0}$$

$$\Delta \phi=-\int_A^B \mathbf{E} \cdot d \mathbf{s}$$

有限元方法代写

tatistics-lab作为专业的留学生服务机构，多年来已为美国、英国、加拿大、澳洲等留学热门地的学生提供专业的学术服务，包括但不限于Essay代写，Assignment代写，Dissertation代写，Report代写，小组作业代写，Proposal代写，Paper代写，Presentation代写，计算机作业代写，论文修改和润色，网课代做，exam代考等等。写作范围涵盖高中，本科，研究生等海外留学全阶段，辐射金融，经济学，会计学，审计学，管理学等全球99%专业科目。写作团队既有专业英语母语作者，也有海外名校硕博留学生，每位写作老师都拥有过硬的语言能力，专业的学科背景和学术写作经验。我们承诺100%原创，100%专业，100%准时，100%满意。

MATLAB代写

MATLAB 是一种用于技术计算的高性能语言。它将计算、可视化和编程集成在一个易于使用的环境中，其中问题和解决方案以熟悉的数学符号表示。典型用途包括：数学和计算算法开发建模、仿真和原型制作数据分析、探索和可视化科学和工程图形应用程序开发，包括图形用户界面构建MATLAB 是一个交互式系统，其基本数据元素是一个不需要维度的数组。这使您可以解决许多技术计算问题，尤其是那些具有矩阵和向量公式的问题，而只需用 C 或 Fortran 等标量非交互式语言编写程序所需的时间的一小部分。MATLAB 名称代表矩阵实验室。MATLAB 最初的编写目的是提供对由 LINPACK 和 EISPACK 项目开发的矩阵软件的轻松访问，这两个项目共同代表了矩阵计算软件的最新技术。MATLAB 经过多年的发展，得到了许多用户的投入。在大学环境中，它是数学、工程和科学入门和高级课程的标准教学工具。在工业领域，MATLAB 是高效研究、开发和分析的首选工具。MATLAB 具有一系列称为工具箱的特定于应用程序的解决方案。对于大多数 MATLAB 用户来说非常重要，工具箱允许您学习应用专业技术。工具箱是 MATLAB 函数（M 文件）的综合集合，可扩展 MATLAB 环境以解决特定类别的问题。可用工具箱的领域包括信号处理、控制系统、神经网络、模糊逻辑、小波、仿真等。

物理代写|电磁学代写electromagnetism代考|ELEC3104

statistics-lab™ 为您的留学生涯保驾护航 在代写电磁学electromagnetism方面已经树立了自己的口碑, 保证靠谱, 高质且原创的统计Statistics代写服务。我们的专家在代写电磁学electromagnetism代写方面经验极为丰富，各种代写电磁学electromagnetism相关的作业也就用不着说。

• Statistical Inference 统计推断
• Statistical Computing 统计计算
• (Generalized) Linear Models 广义线性模型
• Statistical Machine Learning 统计机器学习
• Longitudinal Data Analysis 纵向数据分析
• Foundations of Data Science 数据科学基础

物理代写|电磁学代写electromagnetism代考|Motion in Uniform Electric Field

Suppose a charge particle of mass $m$ and charge $q$ is moving in a uniform electric field $\mathbf{E}$. Electric field $\mathbf{E}$ exerts on a particle placed in it the force
$$\mathbf{F}=q \mathbf{E}$$

If that force is equal to the resultant force exerted on the particle, it causes the particle to accelerate, based on Newton’s second law:
$$m \mathbf{a}=q \mathbf{E}$$
The acceleration gained by the charge is given as
$$\mathbf{a}=\frac{q}{m} \mathbf{E}$$
Therefore, if $\mathbf{E}$ is uniform (that is, constant in magnitude and direction), then a is constant. Furthermore, if the particle has a positive charge, then its acceleration is in the direction of the electric field. On the other hand, if the particle has a negative charge, then its acceleration is in the direction opposite the electric field.

物理代写|电磁学代写electromagnetism代考|Uniform Electric Field

The electric flux concept describes quantitatively the electric lines. The number of field lines per unit area (also called line density) going through a rectangular surface of area $A$, which is perpendicular to the field, is proportional to the magnitude of electric field, E, as shown in Fig. 2.1. Furthermore, the total number of lines penetrating the surface is proportional to the product $|\mathbf{E}|$ A. By definition, the product of the magnitude of electric field $|\mathbf{E}|$ and surface area $A$ perpendicular to the field is called the electric flux:
$$\Phi_E=|\mathbf{E}| A$$
Using Eq. (2.1), from the SI units of $E$ and $A$, we derive the SI units of the electric flux:
$$[E]=\left[\frac{\mathrm{N}}{\mathrm{C}}\right],[A]=\left[\mathrm{m}^2\right]$$

Thus, we obtain SI units of $\Phi_E$ :
$$\left[\Phi_E\right]=\left[\frac{\mathrm{N} \cdot \mathrm{m}^2}{\mathrm{C}}\right]$$
Note that the electric flux is proportional to the number of electric field lines penetrating some surface.

Moreover, consider the electric flux on any surface with an arbitrary orientation with respect to electric field $\mathbf{E}$, as shown in Fig. 2.2. Electric flux going through the surface (with area $A$ ) not perpendicular to $\mathbf{E}$ is smaller than the product $|\mathbf{E}| A$. That is, the number of lines that cross this area $A$ is equal to the number of lines that cross the area $A^{\prime}=A \cos \theta$, which is a projection of $A$ aligned perpendicular to the field. Mathematically, the electric flux is given by (Fig. 2.2)
$$\Phi_E=|\mathbf{E}| A^{\prime}=|\mathbf{E}| A \cos \theta$$
From the definition, Eq. (2.4), we can say that the maximum electric flux is achieved when $\theta=0^{\circ}$; that is, the surface is perpendicular to $\mathbf{E}$ : $\Phi_F^{\max }=|\mathbf{E}| A$ (see also Eq. (2.1)). Or, equivalently, when normal vector $\mathbf{n}$ to the surface is parallel to E. On the other hand, the minimum electric flux is achieved when $\theta=90^{\circ}$, that is, the surface is parallel to $\mathbf{E}: \Phi_E^{\min }=0$. In this case, normal vector $\mathbf{n}$ to the surface is perpendicular to $\mathbf{E}$. In general, denoting the vector $\mathbf{A}=A \mathbf{n}$, we can write
$$\Phi_E=\mathbf{E} \cdot \mathbf{A}$$

电磁学代考

物理代写|电磁学代写electromagnetism代考|Motion in Uniform Electric Field

$$\mathbf{F}=q \mathbf{E}$$

$$m \mathbf{a}=q \mathbf{E}$$

$$\mathbf{a}=\frac{q}{m} \mathbf{E}$$

物理代写|电磁学代写electromagnetism代考|Uniform Electric Field

$$\Phi_E=|\mathbf{E}| A$$

$$[E]=\left[\frac{\mathrm{N}}{\mathrm{C}}\right],[A]=\left[\mathrm{m}^2\right]$$

$$\left[\Phi_E\right]=\left[\frac{\mathrm{N} \cdot \mathrm{m}^2}{\mathrm{C}}\right]$$

$$\Phi_E=|\mathbf{E}| A^{\prime}=|\mathbf{E}| A \cos \theta$$

$$\Phi_E=\mathbf{E} \cdot \mathbf{A}$$

有限元方法代写

tatistics-lab作为专业的留学生服务机构，多年来已为美国、英国、加拿大、澳洲等留学热门地的学生提供专业的学术服务，包括但不限于Essay代写，Assignment代写，Dissertation代写，Report代写，小组作业代写，Proposal代写，Paper代写，Presentation代写，计算机作业代写，论文修改和润色，网课代做，exam代考等等。写作范围涵盖高中，本科，研究生等海外留学全阶段，辐射金融，经济学，会计学，审计学，管理学等全球99%专业科目。写作团队既有专业英语母语作者，也有海外名校硕博留学生，每位写作老师都拥有过硬的语言能力，专业的学科背景和学术写作经验。我们承诺100%原创，100%专业，100%准时，100%满意。

MATLAB代写

MATLAB 是一种用于技术计算的高性能语言。它将计算、可视化和编程集成在一个易于使用的环境中，其中问题和解决方案以熟悉的数学符号表示。典型用途包括：数学和计算算法开发建模、仿真和原型制作数据分析、探索和可视化科学和工程图形应用程序开发，包括图形用户界面构建MATLAB 是一个交互式系统，其基本数据元素是一个不需要维度的数组。这使您可以解决许多技术计算问题，尤其是那些具有矩阵和向量公式的问题，而只需用 C 或 Fortran 等标量非交互式语言编写程序所需的时间的一小部分。MATLAB 名称代表矩阵实验室。MATLAB 最初的编写目的是提供对由 LINPACK 和 EISPACK 项目开发的矩阵软件的轻松访问，这两个项目共同代表了矩阵计算软件的最新技术。MATLAB 经过多年的发展，得到了许多用户的投入。在大学环境中，它是数学、工程和科学入门和高级课程的标准教学工具。在工业领域，MATLAB 是高效研究、开发和分析的首选工具。MATLAB 具有一系列称为工具箱的特定于应用程序的解决方案。对于大多数 MATLAB 用户来说非常重要，工具箱允许您学习应用专业技术。工具箱是 MATLAB 函数（M 文件）的综合集合，可扩展 MATLAB 环境以解决特定类别的问题。可用工具箱的领域包括信号处理、控制系统、神经网络、模糊逻辑、小波、仿真等。

物理代写|电磁学代写electromagnetism代考|PHYC20014

statistics-lab™ 为您的留学生涯保驾护航 在代写电磁学electromagnetism方面已经树立了自己的口碑, 保证靠谱, 高质且原创的统计Statistics代写服务。我们的专家在代写电磁学electromagnetism代写方面经验极为丰富，各种代写电磁学electromagnetism相关的作业也就用不着说。

• Statistical Inference 统计推断
• Statistical Computing 统计计算
• (Generalized) Linear Models 广义线性模型
• Statistical Machine Learning 统计机器学习
• Longitudinal Data Analysis 纵向数据分析
• Foundations of Data Science 数据科学基础

物理代写|电磁学代写electromagnetism代考|Force Fields

The field forces act through space, producing an effect even when no physical contact between the objects occurs. As an example, we can mention the gravitational field. Michael Faraday developed a similar approach to electric forces. That is, an electric field exists in the region of space around any charged body, and when another charged body is inside this region of the electric field, an electric force acts on it.

Definition 1.2 The electric field $\mathbf{E}$ at a point in space is defined as the electric force $\mathbf{F}_e$ acting on a positive test charge $q_0$ placed at that point divided by the magnitude of the test charge:
$$\mathbf{E}=\frac{\mathbf{F}_e}{q_0}$$

The vector $\mathbf{E}$ has the SI units of newtons per coulomb (N/C). Figure $1.3$ illustrates the electric field $\mathbf{E}$ created by a positively charged sphere with total charge $Q$ at the positive test charge $q_0$. Here, we have assumed that the test charge $q_0$ is small enough that it does not disturb the charge distribution of the sphere responsible for the electric field.

Note that $\mathbf{E}$ is the field produced by some charge external to the test charge, and it is not the field produced by the test charge itself. Also, note that the existence of an electric field is a property of its source. For example, every electron comes with its electric field. An electric field exists at a point if a test charge at rest at that point experiences an electric force. The electric field direction is the direction of the force on a positive test charge placed in the field. Once we know the magnitude and direction of the electric field at some point, the electric force exerted on any charged particle (either positive or negative) placed at that point can be calculated. The electric field exists at some point space, including the free space, independent of the existence of another test charge at that point.

To determine the direction of electric field, consider a point charge $q$ located some distance $r$ from a test positive charge $q_0$ located at a point $P$, as shown in Fig. 1.4. field Coulomb’s law defines the force exerted by $q$ on $q_0$ as
$$\mathbf{F}_e=k_e \frac{q q_0}{r^2} \hat{\mathbf{r}}$$

物理代写|电磁学代写electromagnetism代考|Superposition Principle

According to superposition principle, at any point $P$, the total electric field due to a set of discrete point charges, $q_1, q_2, \ldots, q_N$, positive and negative charges, is equal to the sum of the individual charge electric field vectors (see Fig. 1.5). Mathematically, we can write
$$\mathbf{E}(\mathbf{r})=\sum_{i=1}^N \mathbf{E}i=\sum{i=1}^N k_e \frac{q_i}{\left|\mathbf{r}-\mathbf{r}_i\right|^2} \hat{\mathbf{r}}_i$$
In Eq. (1.12), $\left|\mathbf{r}-\mathbf{r}_i\right|$ is the distance from $q_i$ to the point $P$ (the location of a test charge), where $\mathbf{r}$ is the position vector of the point $P$ with respect to some reference frame, as indicated in Fig. 1.5, and $\mathbf{r}_i$ is the position vector of the charge $i$ in that reference frame. Furthermore, $\hat{\mathbf{r}}_i$ is a unit vector directed from $q_i$ toward $P$.

Note that in Eq. (1.12) the dependence of $\mathbf{E}$ on only position vector of point $P, \mathbf{r}$, assumes a static configuration of the charges in space. That is, for some other configuration distribution of charges in space, $\mathbf{E}$ at the same point $P$ may be different. Note that often for convenience, Eq. (1.12) is also written as $$\mathbf{E}(\mathbf{r})=\sum_{i=1}^N k_e \frac{q_i\left(\mathbf{r}-\mathbf{r}_i\right)}{\left|\mathbf{r}-\mathbf{r}_i\right|^3}$$
where
$$\hat{\mathbf{r}}_i=\frac{\mathbf{r}-\mathbf{r}_i}{\left|\mathbf{r}-\mathbf{r}_i\right|}$$
If the distances between charges in a set of charges are much smaller, compare with the distance of the set from a point where the electric field is to be calculated, then charge distribution is continuous.

电磁学代考

物理代写|电磁学代写electromagnetism代考|Force Fields

$$\mathbf{E}=\frac{\mathbf{F}_e}{q_0}$$

$$\hat{\mathbf{r}}_i=\frac{\mathbf{r}-\mathbf{r}_i}{\left|\mathbf{r}-\mathbf{r}_i\right|}$$

有限元方法代写

tatistics-lab作为专业的留学生服务机构，多年来已为美国、英国、加拿大、澳洲等留学热门地的学生提供专业的学术服务，包括但不限于Essay代写，Assignment代写，Dissertation代写，Report代写，小组作业代写，Proposal代写，Paper代写，Presentation代写，计算机作业代写，论文修改和润色，网课代做，exam代考等等。写作范围涵盖高中，本科，研究生等海外留学全阶段，辐射金融，经济学，会计学，审计学，管理学等全球99%专业科目。写作团队既有专业英语母语作者，也有海外名校硕博留学生，每位写作老师都拥有过硬的语言能力，专业的学科背景和学术写作经验。我们承诺100%原创，100%专业，100%准时，100%满意。

MATLAB代写

MATLAB 是一种用于技术计算的高性能语言。它将计算、可视化和编程集成在一个易于使用的环境中，其中问题和解决方案以熟悉的数学符号表示。典型用途包括：数学和计算算法开发建模、仿真和原型制作数据分析、探索和可视化科学和工程图形应用程序开发，包括图形用户界面构建MATLAB 是一个交互式系统，其基本数据元素是一个不需要维度的数组。这使您可以解决许多技术计算问题，尤其是那些具有矩阵和向量公式的问题，而只需用 C 或 Fortran 等标量非交互式语言编写程序所需的时间的一小部分。MATLAB 名称代表矩阵实验室。MATLAB 最初的编写目的是提供对由 LINPACK 和 EISPACK 项目开发的矩阵软件的轻松访问，这两个项目共同代表了矩阵计算软件的最新技术。MATLAB 经过多年的发展，得到了许多用户的投入。在大学环境中，它是数学、工程和科学入门和高级课程的标准教学工具。在工业领域，MATLAB 是高效研究、开发和分析的首选工具。MATLAB 具有一系列称为工具箱的特定于应用程序的解决方案。对于大多数 MATLAB 用户来说非常重要，工具箱允许您学习应用专业技术。工具箱是 MATLAB 函数（M 文件）的综合集合，可扩展 MATLAB 环境以解决特定类别的问题。可用工具箱的领域包括信号处理、控制系统、神经网络、模糊逻辑、小波、仿真等。

物理代写|电磁学代写electromagnetism代考|PHY53040

statistics-lab™ 为您的留学生涯保驾护航 在代写电磁学electromagnetism方面已经树立了自己的口碑, 保证靠谱, 高质且原创的统计Statistics代写服务。我们的专家在代写电磁学electromagnetism代写方面经验极为丰富，各种代写电磁学electromagnetism相关的作业也就用不着说。

• Statistical Inference 统计推断
• Statistical Computing 统计计算
• (Generalized) Linear Models 广义线性模型
• Statistical Machine Learning 统计机器学习
• Longitudinal Data Analysis 纵向数据分析
• Foundations of Data Science 数据科学基础

物理代写|电磁学代写electromagnetism代考|Electrical Charges

There exist several simple experiments to demonstrate the existence of electrical charges and forces. For example,

1. When we comb our hair on a dry day, we find that the comb attracts pieces of paper.
2. The same effect of attracting pieces of paper occurs when materials such as glass or rubber are rubbed with silk or fur.

As a general rule, for every material behaving in that way, we can say that it is electrified, or it becomes electrically charged.

Benjamin Franklin (1706-1790) found that there exist two types of electric charges, namely positive and negative. The following experiment can be used to demonstrate his finding. Suppose that we rubber with fur a hard rubber rod. In addition, we rub a glass rod with silk material. Then, if the glass rod is brought near the rubber rod, we will observe that the two attract each other. However, if we bring near each other two charged rubber rods or two charged glass rods, then the two repel each other. This experiment indicates the existence of two different states of electrification for the rubber and glass. Furthermore, it finds that like charges repel each other and unlike charges attract each other.

By convention, the electric charge on the glass rod is positive, and that on the rubber rod is negative. Based on that convention, any charged object repelled by another charged object must have the same sign of charge with it, and any charged object attracted by another charged object must have an opposite sign of charge. It is important to note that the electricity model of Franklin implies that electric charge is always conserved. That is, an electrified state (positive or negative) is due to the charge transfer from one object to the other. In other words, when an object gains some amount of positive/negative charge, then the other gains an equal amount of the electric charge of the opposite sign.

Robert Millikan (1868-1953), in 1909, discovered that electric charge always appears as a multiple integer of a fundamental amount of charge, called $e$ such that the electric charge $q$, which is a standard symbol for the charge, is quantized as
$$q=N e$$
Here, $N$ is an integer number, $N=0, \pm 1, \pm 2, \ldots$.

物理代写|电磁学代写electromagnetism代考|Coulomb’s Law

Based on an experiment performed by Coulomb, the electric force between two charged particles at rest is proportional to the inverse of the square of distance $r$ between them and directed along the line joining the two particles. In addition, the electric force is proportional to the charges $q_1$ and $q_2$ on each particle. Also, the electric force is attractive if the charges are of opposite sign and repulsive if the charges have the same sign. That is known as Coulomb’s Law.

Definition 1.1 Force is proportional to the product of the magnitudes of the charges and inversely proportional to the square of the distance between them. Mathematically, the law may be written as
$$F=k_e \frac{\left|q_1\right|\left|q_2\right|}{r^2}$$
In Eq. (1.2), $k_e$ is the Coulomb constant. Note that, in SI, the unit of charge is the coulomb (C). Therefore, the Coulomb constant $k_e$ in SI units has the value
$$k_e=8.9875 \times 10^9 \mathrm{~N} \cdot \mathrm{m}^2 / \mathrm{C}^2$$
Often, the constant is written as $$k_e=\frac{1}{4 \pi \epsilon_0}$$
where $\epsilon_0$ is the permittivity of free space given by
$$\epsilon_0=8.8542 \times 10^{-12} \mathrm{C}^2 / \mathrm{N} \cdot \mathrm{m}^2$$
Coulomb’s force is a vector; hence it has a magnitude expressed by Eq. (1.2) and a direction. Therefore, the Coulomb’s law can be expressed in vector form concerning the electric force, $\mathbf{F}{12}$, exerted by the charge $q_1$ (positive or negative) on another charge $q_2$ (positive or negative) as $$\mathbf{F}{12}=k_e \frac{q_1 q_2}{r^2} \hat{\mathbf{r}}$$
In Eq. (1.6), $\hat{\mathbf{r}}$ denotes a unit vector pointing from $q_1$ to $q_2$. Note that based on the Newton’s third law, the electric force, $\mathbf{F}{21}$, exerted by a charge $q_2$ (positive or negative) on a second charge $q_2$ (positive or negative) is $$\mathbf{F}{21}=-\mathbf{F}_{12}$$

电磁学代考

$$在公式（1.6）中，hat{\mathbf{r}}表示一个单位矢量，指向从q 统计代写请认准statistics-lab™. statistics-lab™为您的留学生涯保驾护航。 金融工程代写 金融工程是使用数学技术来解决金融问题。金融工程使用计算机科学、统计学、经济学和应用数学领域的工具和知识来解决当前的金融问题，以及设计新的和创新的金融产品。 非参数统计代写 非参数统计指的是一种统计方法，其中不假设数据来自于由少数参数决定的规定模型；这种模型的例子包括正态分布模型和线性回归模型。 广义线性模型代考 广义线性模型（GLM）归属统计学领域，是一种应用灵活的线性回归模型。该模型允许因变量的偏差分布有除了正态分布之外的其它分布。 术语 广义线性模型（GLM）通常是指给定连续和/或分类预测因素的连续响应变量的常规线性回归模型。它包括多元线性回归，以及方差分析和方差分析（仅含固定效应）。 有限元方法代写 有限元方法（FEM）是一种流行的方法，用于数值解决工程和数学建模中出现的微分方程。典型的问题领域包括结构分析、传热、流体流动、质量运输和电磁势等传统领域。 有限元是一种通用的数值方法，用于解决两个或三个空间变量的偏微分方程（即一些边界值问题）。为了解决一个问题，有限元将一个大系统细分为更小、更简单的部分，称为有限元。这是通过在空间维度上的特定空间离散化来实现的，它是通过构建对象的网格来实现的：用于求解的数值域，它有有限数量的点。边界值问题的有限元方法表述最终导致一个代数方程组。该方法在域上对未知函数进行逼近。[1] 然后将模拟这些有限元的简单方程组合成一个更大的方程系统，以模拟整个问题。然后，有限元通过变化微积分使相关的误差函数最小化来逼近一个解决方案。 tatistics-lab作为专业的留学生服务机构，多年来已为美国、英国、加拿大、澳洲等留学热门地的学生提供专业的学术服务，包括但不限于Essay代写，Assignment代写，Dissertation代写，Report代写，小组作业代写，Proposal代写，Paper代写，Presentation代写，计算机作业代写，论文修改和润色，网课代做，exam代考等等。写作范围涵盖高中，本科，研究生等海外留学全阶段，辐射金融，经济学，会计学，审计学，管理学等全球99%专业科目。写作团队既有专业英语母语作者，也有海外名校硕博留学生，每位写作老师都拥有过硬的语言能力，专业的学科背景和学术写作经验。我们承诺100%原创，100%专业，100%准时，100%满意。 随机分析代写 随机微积分是数学的一个分支，对随机过程进行操作。它允许为随机过程的积分定义一个关于随机过程的一致的积分理论。这个领域是由日本数学家伊藤清在第二次世界大战期间创建并开始的。 时间序列分析代写 随机过程，是依赖于参数的一组随机变量的全体，参数通常是时间。 随机变量是随机现象的数量表现，其时间序列是一组按照时间发生先后顺序进行排列的数据点序列。通常一组时间序列的时间间隔为一恒定值（如1秒，5分钟，12小时，7天，1年），因此时间序列可以作为离散时间数据进行分析处理。研究时间序列数据的意义在于现实中，往往需要研究某个事物其随时间发展变化的规律。这就需要通过研究该事物过去发展的历史记录，以得到其自身发展的规律。 回归分析代写 多元回归分析渐进（Multiple Regression Analysis Asymptotics）属于计量经济学领域，主要是一种数学上的统计分析方法，可以分析复杂情况下各影响因素的数学关系，在自然科学、社会和经济学等多个领域内应用广泛。 MATLAB代写 MATLAB 是一种用于技术计算的高性能语言。它将计算、可视化和编程集成在一个易于使用的环境中，其中问题和解决方案以熟悉的数学符号表示。典型用途包括：数学和计算算法开发建模、仿真和原型制作数据分析、探索和可视化科学和工程图形应用程序开发，包括图形用户界面构建MATLAB 是一个交互式系统，其基本数据元素是一个不需要维度的数组。这使您可以解决许多技术计算问题，尤其是那些具有矩阵和向量公式的问题，而只需用 C 或 Fortran 等标量非交互式语言编写程序所需的时间的一小部分。MATLAB 名称代表矩阵实验室。MATLAB 最初的编写目的是提供对由 LINPACK 和 EISPACK 项目开发的矩阵软件的轻松访问，这两个项目共同代表了矩阵计算软件的最新技术。MATLAB 经过多年的发展，得到了许多用户的投入。在大学环境中，它是数学、工程和科学入门和高级课程的标准教学工具。在工业领域，MATLAB 是高效研究、开发和分析的首选工具。MATLAB 具有一系列称为工具箱的特定于应用程序的解决方案。对于大多数 MATLAB 用户来说非常重要，工具箱允许您学习应用专业技术。工具箱是 MATLAB 函数（M 文件）的综合集合，可扩展 MATLAB 环境以解决特定类别的问题。可用工具箱的领域包括信号处理、控制系统、神经网络、模糊逻辑、小波、仿真等。 物理代写|电磁学代写electromagnetism代考|ELEC3104 如果你也在 怎样代写电磁学electromagnetism这个学科遇到相关的难题，请随时右上角联系我们的24/7代写客服。 电磁学是电荷、磁矩和电磁场之间的物理互动。电磁场可以是静态的，缓慢变化的，或形成波。电磁波一般被称为光，遵守光学定律。 statistics-lab™ 为您的留学生涯保驾护航 在代写电磁学electromagnetism方面已经树立了自己的口碑, 保证靠谱, 高质且原创的统计Statistics代写服务。我们的专家在代写电磁学electromagnetism代写方面经验极为丰富，各种代写电磁学electromagnetism相关的作业也就用不着说。 我们提供的电磁学electromagnetism及其相关学科的代写，服务范围广, 其中包括但不限于: • Statistical Inference 统计推断 • Statistical Computing 统计计算 • Advanced Probability Theory 高等概率论 • Advanced Mathematical Statistics 高等数理统计学 • (Generalized) Linear Models 广义线性模型 • Statistical Machine Learning 统计机器学习 • Longitudinal Data Analysis 纵向数据分析 • Foundations of Data Science 数据科学基础 物理代写|电磁学代写electromagnetism代考|Basic Phenomena Let a stationary source charge q be located at a point \mathbf{x}_q. We measure a field of force around \mathbf{x}_q by means of a test charge q^{\prime}. Keeping the source charge at \mathrm{x}_q and putting q^{\prime} at different points in space, we see different forces acting on q^{\prime}; it is by this procedure that we define a field. If the source charge is reduced (increased) by a certain factor, the force acting on q^{\prime} is found to decrease (increase) by the same factor. The force acting on the charge q^{\prime}, divided by this charge, gives a field, which we call an electric field:$$
\frac{\mathbf{F}(\mathbf{x})}{q^{\prime}}=\mathbf{E}(\mathbf{x})
$$\mathbf{E}(\mathbf{x}) is a property of the source charge and is independent of the test charge q^{\prime}; it is given by Coulomb’s law, which, in the Gaussian system of units, can be expressed as follows:$$
\mathbf{E}(\mathbf{x})=-\nabla_x \frac{q}{\left|\mathbf{x}-\mathbf{x}_q\right|}=\frac{q \mathbf{n}}{\left|\mathbf{x}-\mathbf{x}_q\right|^2}
$$where (see Fig. 2.1)$$
\mathbf{n}=\frac{\mathbf{x}-\mathbf{x}_q}{\left|\mathbf{x}-\mathbf{x}_q\right|}
$$We can write, in general$$
\mathbf{E}(\mathbf{x})=-\nabla \phi(\mathbf{x})
$$where \phi(\mathbf{x}) is called potential and is given by$$
\phi(\mathbf{x})=\frac{q}{\left|\mathbf{x}-\mathbf{x}_q\right|}
$$We now examine two important principles: 物理代写|电磁学代写electromagnetism代考|The Superposition Principle Given two charges q_1 and q_2 at two different positions (see Fig. 2.2), the potential at point \mathrm{x} is given by$$
\phi(\mathbf{x})=\phi_1(\mathbf{x})+\phi_2(\mathbf{x})
$$where \phi_1 and \phi_2 are the potentials due to the charges q_1 and q_2, respectively. Therefore,$$
\mathbf{E}(\mathbf{x})=-\nabla \phi(\mathbf{x})=-\nabla \phi_1(\mathbf{x})-\nabla \phi_2(\mathbf{x})=\mathbf{E}_1(\mathbf{x})+\mathbf{E}_2(\mathbf{x})
$$We define the field at \mathbf{x} by means of a charge q^{\prime}. There is, however, no difference in concept between charge q and charge q^{\prime} (see Fig. 2.3). We can consider q as the test charge and q^{\prime} as the source charge. In accordance with Newton’s third law,$$
\mathbf{F}\left(\text { on } q^{\prime} \text { at } \mathbf{x}\right)=-\mathbf{F}\left(\text { on } q \text { at } \mathbf{x}_q\right)
$$or$$
\mathbf{E}(\mathbf{x}) q^{\prime}=-\mathbf{E}\left(\mathbf{x}_q\right) q
$$We should not forget that the experimental quantities that we measure are the forces; the concept of fields derives from these principal parameters. 电磁学代考 物理代写|电磁学代写electromagnetism代考|Basic Phenomena 让固定源充电 q 位于一点 \mathbf{x}_q. 我们测量周围的力场 \mathbf{x}_q 通过测试费用 q^{\prime}. 将源电荷保持在 \mathrm{x}_q 并把 q^{\prime} 在空间的不同点， 我们看到不同的力作用于 q^{\prime}; 正是通过这个过程，我们定义了一个字段。如果源电荷减少 (增加) 某个因子，则作 用在 q^{\prime} 发现减少 (增加) 相同的因素。 作用在电荷上的力 q^{\prime} ，除以这个电荷，得到一个场，我们称之为电场:$$
\frac{\mathbf{F}(\mathbf{x})}{q^{\prime}}=\mathbf{E}(\mathbf{x})
$$\mathbf{E}(\mathbf{x}) 是源电荷的属性并且独立于测试电荷 q^{\prime}; 它由库仑定律给出，在高斯单位系统中， 可以表示如下:$$
\mathbf{E}(\mathbf{x})=-\nabla_x \frac{q}{\left|\mathbf{x}-\mathbf{x}_q\right|}=\frac{q \mathbf{n}}{\left|\mathbf{x}-\mathbf{x}_q\right|^2}
$$其中 (见图 2.1)$$
\mathbf{n}=\frac{\mathbf{x}-\mathbf{x}_q}{\left|\mathbf{x}-\mathbf{x}_q\right|}
$$一般来说，我们可以写$$
\mathbf{E}(\mathbf{x})=-\nabla \phi(\mathbf{x})
$$在哪里 \phi(\mathbf{x}) 称为势能，由下式给出$$
\phi(\mathbf{x})=\frac{q}{\left|\mathbf{x}-\mathbf{x}_q\right|}
$$我们现在检查两个重要原则: 物理代写|电磁学代写electromagnetism代考|The Superposition Principle 鉴于两项指控 q_1 和 q_2 在两个不同的位置 (见图 2.2)，点的电位X是（谁) 给的$$
\phi(\mathbf{x})=\phi_1(\mathbf{x})+\phi_2(\mathbf{x})
$$在哪里 \phi_1 和 \phi_2 是由于电荷的电位 q_1 和 q_2 ，分别。所以，$$
\mathbf{E}(\mathbf{x})=-\nabla \phi(\mathbf{x})=-\nabla \phi_1(\mathbf{x})-\nabla \phi_2(\mathbf{x})=\mathbf{E}_1(\mathbf{x})+\mathbf{E}_2(\mathbf{x})
$$我们将字段定义为 \mathbf{x} 通过收费 q^{\prime}. 但是，电荷之间在概念上没有区别 q 并收费 q^{\prime} (见图 2.3)。我们可以考虑 q 作为测 试费用和 q^{\prime} 作为源电荷。根据牛顿第三定律，$$
\mathbf{F}\left(\text { on } q^{\prime} \text { at } \mathbf{x}\right)=-\mathbf{F}\left(\text { on } q \text { at } \mathbf{x}_q\right)
$$或者$$
\mathbf{E}(\mathbf{x}) q^{\prime}=-\mathbf{E}\left(\mathbf{x}_q\right) q


有限元方法代写

tatistics-lab作为专业的留学生服务机构，多年来已为美国、英国、加拿大、澳洲等留学热门地的学生提供专业的学术服务，包括但不限于Essay代写，Assignment代写，Dissertation代写，Report代写，小组作业代写，Proposal代写，Paper代写，Presentation代写，计算机作业代写，论文修改和润色，网课代做，exam代考等等。写作范围涵盖高中，本科，研究生等海外留学全阶段，辐射金融，经济学，会计学，审计学，管理学等全球99%专业科目。写作团队既有专业英语母语作者，也有海外名校硕博留学生，每位写作老师都拥有过硬的语言能力，专业的学科背景和学术写作经验。我们承诺100%原创，100%专业，100%准时，100%满意。

MATLAB代写

MATLAB 是一种用于技术计算的高性能语言。它将计算、可视化和编程集成在一个易于使用的环境中，其中问题和解决方案以熟悉的数学符号表示。典型用途包括：数学和计算算法开发建模、仿真和原型制作数据分析、探索和可视化科学和工程图形应用程序开发，包括图形用户界面构建MATLAB 是一个交互式系统，其基本数据元素是一个不需要维度的数组。这使您可以解决许多技术计算问题，尤其是那些具有矩阵和向量公式的问题，而只需用 C 或 Fortran 等标量非交互式语言编写程序所需的时间的一小部分。MATLAB 名称代表矩阵实验室。MATLAB 最初的编写目的是提供对由 LINPACK 和 EISPACK 项目开发的矩阵软件的轻松访问，这两个项目共同代表了矩阵计算软件的最新技术。MATLAB 经过多年的发展，得到了许多用户的投入。在大学环境中，它是数学、工程和科学入门和高级课程的标准教学工具。在工业领域，MATLAB 是高效研究、开发和分析的首选工具。MATLAB 具有一系列称为工具箱的特定于应用程序的解决方案。对于大多数 MATLAB 用户来说非常重要，工具箱允许您学习应用专业技术。工具箱是 MATLAB 函数（M 文件）的综合集合，可扩展 MATLAB 环境以解决特定类别的问题。可用工具箱的领域包括信号处理、控制系统、神经网络、模糊逻辑、小波、仿真等。