# Understanding Eq. 2.18 & Eq. 2.5 in Jackson's ED Book

• rbwang1225
D. Jackson's book, as it requires a deep understanding of the underlying theory.In summary, the conversation discusses two equations from Jackson's ED book, specifically eq. 2.18 and eq. 2.5. While they may seem similar, they are actually used for different purposes: eq. 2.5 is for finding surface charge based on potential, while eq. 2.18 is for the Dirichlet boundary condition using a GF. This is considered a difficult concept and requires a strong understanding of the underlying theory.
rbwang1225
In Jackson's ED book, he mentioned eq. 2.18 is essentially the same as eq. 2.5. What I don't understand is that in eq. 2.18 it is the position of the unit source to be differentiated while in eq. 2.5 it is the observation point. Is this O.K.?

It might help if you provided the examples you were talking about. I know I don't have this book that you are referring to.

The two equations are for different things. That is why there are the two equations.
(2.5) is to get the surface charge for a given potential.
(2.18) is what is needed for the Dirichlet boundary condition using a GF.
That is one of the (many) difficult sections of J.

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## What are Eq. 2.18 and Eq. 2.5 in Jackson's ED Book?

Eq. 2.18 and Eq. 2.5 refer to equations in the book "Classical Electrodynamics" written by John David Jackson. These equations are used to describe the electric and magnetic fields in a vacuum, and are fundamental to understanding electromagnetic waves and their behavior.

## Why are Eq. 2.18 and Eq. 2.5 important in the field of electrodynamics?

Eq. 2.18 and Eq. 2.5 are important because they provide a mathematical description of the behavior of electric and magnetic fields. These equations are used to solve problems related to electromagnetic waves, such as calculating the propagation of radio waves or the behavior of light.

## What is the difference between Eq. 2.18 and Eq. 2.5?

The main difference between Eq. 2.18 and Eq. 2.5 is that Eq. 2.18 describes the electric field in terms of its divergence, while Eq. 2.5 describes the magnetic field in terms of its curl. This reflects the fact that electric fields are created by electric charges, while magnetic fields are created by moving electric charges.

## How are Eq. 2.18 and Eq. 2.5 derived?

Eq. 2.18 and Eq. 2.5 are derived from Maxwell's equations, which are a set of four equations that describe the behavior of electric and magnetic fields. These equations were first formulated by James Clerk Maxwell in the 19th century and have been refined and expanded upon by many scientists since then.

## What are some real-world applications of Eq. 2.18 and Eq. 2.5?

Eq. 2.18 and Eq. 2.5 are used in a wide range of real-world applications, including telecommunications, radar technology, and medical imaging. These equations are also fundamental to our understanding of light and its behavior, which has led to advancements in technologies such as lasers, solar panels, and fiber optics.

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