Why Does j.ds Have Closed Integral on Electromagnetics Equation?

In summary, the conversation discusses the notation of 'closed integral' on an equation and its relation to a continuity equation. It is used to calculate the change in charge within a specified region of space, where the surface enclosing the region is considered closed.
  • #1
bhanesh
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Why j.ds has ' closed integral ' on below equation

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  • #3
I think this is some kind of continuity equation.Its considering a region of space with some charge inside it.Because charge can't be created or destroyed,the only thing which can cause the amount of charge to change is a current and so we should have a surface integral of current density.But because we're interested in a region of space,the surface is the one enclosing that region which is of course closed.
 

FAQ: Why Does j.ds Have Closed Integral on Electromagnetics Equation?

1. What is a closed integral on an electromagnetics equation?

A closed integral on an electromagnetics equation is a mathematical concept that is used to calculate the total amount of a certain physical quantity (such as electric or magnetic field) within a closed surface. It is represented by a symbol that looks like a loop or a circle with an arrow on top, and is often used in Maxwell's equations to describe the behavior of electromagnetic fields.

2. Why is a closed integral used in electromagnetics equations?

A closed integral is used in electromagnetics equations because it allows us to calculate the total amount of a physical quantity within a given space, which is important for understanding the behavior and interactions of electromagnetic fields. It is also a useful tool for solving problems in electromagnetics and for predicting the behavior of electromagnetic waves.

3. What are the limitations of using a closed integral in electromagnetics equations?

One limitation of using a closed integral in electromagnetics equations is that it assumes that the electric and magnetic fields are constant within the closed surface, which may not always be the case. Additionally, it does not take into account the effects of changing electric or magnetic fields over time, which can be important in certain situations.

4. Can a closed integral be used for any type of physical quantity?

No, a closed integral is specifically used for calculating the total amount of a vector quantity (such as electric or magnetic field) within a closed surface. It cannot be used for scalar quantities, which do not have a direction associated with them.

5. How is a closed integral different from an open integral?

A closed integral is used to calculate the total amount of a physical quantity within a closed surface, while an open integral is used to calculate the amount of a physical quantity along a specific path or surface. An open integral is also represented by a different symbol, and is used in different contexts than a closed integral.

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