# Solve Electrostatic Problem with Y.K.Lim Problem & Solutions

• dingo_d
In summary, the conversation is discussing a confusion about the electric field equation in Y.K.Lim's book on Electromagnetism. The person is questioning why there is a square in the r term and what e_r stands for. Another person explains that the electric field is not due to a single charge, so it does not need to be proportional to r^2. However, the original person points out that the book still includes the r^2 term in the equation, which may be a typo.
dingo_d

## Homework Statement

I'm looking at Y.K.Lim's Problems and solutions in Electromagnetism and there's one thing that's confusing me:

[PLAIN]http://img545.imageshack.us/img545/2218/capturegb.png

## Homework Equations

Where does the square in r comes from? When in the beginning it says that the electric field is:

$$E=A\frac{e^{-br}}{r}e_r$$ not$$E=A\frac{e^{-br}}{r^2}e_r$$

What am I missing?

And what should $$e_r$$ stand for? Charge?

Last edited by a moderator:
This E-field is not due to a single charge. It is due to a distribution of charges, so it needs not be proportional to r^2. For example, a uniformly charged plane produces uniform E-field on each side of the plane, obviously not proportional to distance^2, correct?
$$e_r$$ is the unit radius vector.

Ok it needs not be proportional to r^2, but why did he put it then? When taking the divergence of the field?

Oh I see. Then it seems to me that it's a typo

Oh, I thought it's something new I didn't know XD

## 1. How do I approach solving an electrostatic problem using Y.K. Lim's method?

Y.K. Lim's method involves breaking down the problem into smaller parts and using the principle of superposition to solve for the total electrostatic potential or field. The steps typically include identifying the charge distribution, determining the boundary conditions, and applying the appropriate equations.

## 2. What are the common mistakes to avoid when using Y.K. Lim's method?

One common mistake is forgetting to account for the boundary conditions, which can greatly affect the overall solution. Another mistake is not properly identifying the charge distribution or using incorrect equations.

## 3. Can Y.K. Lim's method be used for all types of electrostatic problems?

Y.K. Lim's method is most commonly used for solving problems involving point charges or line charges. It can also be used for more complex problems, but may require additional techniques or approximations.

## 4. How can I check if my solution using Y.K. Lim's method is correct?

One way to check the accuracy of your solution is to apply the equations and principles to a simpler case or to use a numerical simulation program. Additionally, checking for continuity and satisfying the boundary conditions can also help verify the solution.

## 5. Are there any tips for improving efficiency when using Y.K. Lim's method?

Breaking down the problem into smaller parts and using symmetry can help simplify the calculations. Additionally, using vector algebra and geometry can also make the process more efficient. It is also important to double check equations and calculations to avoid errors.

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