Griffith's ED Chapter 4 Clarification (Bound Charges)

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In summary, the conversation is about a question regarding the equation used by Griffith to derive the field of a polarized object. The equation in question, 4.8, references equation 3.99 which is the field from a dipole and only depends on the distance from the origin to the point P. The speaker is unsure about how the substitution of 'script r' for distance is made and questions the fairness of this substitution. The other party explains that for distances far from the dipole, the two equations are equivalent and the one using script r is more correct. The conversation ends with the speaker understanding and thanking the other person.
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Jason Williams
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I'm having an issue with the equation that Griffith uses to derive the field of a polarized object. In Chapter 4, Section 2.1, he starts off with equation 4.8 with the 'script r' to denote the distance between a point outside the distribution P (and the origin) and the dipole (and the origin). He references equation 3.99 to 'derive' this, but equation 3.99 is the field from a dipole and only depends on the distance from the origin to the point P. I don't quite understand how he makes this jump.
 
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I think he's using script r to denote distance from the dipole to the point in question because he's no longer dealing with distances far from the dipole where r and script r are basically equivalent.
 
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Okay that's what I figured, but is it fair just to make that substitution? Like why not use the regular equation for the potential?
 
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I mean they're equivalent except for the definition of distance that you use. Technically the one with script r is more correct I think, but for distances far from the dipole you approximate with r.

The equation is an approximation anyway, but there are orders of correctness I guess.
 
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Okay cool, got it. Thanks so much!
 

FAQ: Griffith's ED Chapter 4 Clarification (Bound Charges)

What is Griffith's ED Chapter 4 Clarification?

Griffith's ED Chapter 4 Clarification is a concept used in electromagnetic theory that explains the behavior of bound charges, which are charges that are not free to move within a material.

Why is it important to understand Griffith's ED Chapter 4 Clarification?

Understanding Griffith's ED Chapter 4 Clarification is important because it helps us to accurately model and predict the behavior of electromagnetic fields in materials, which is crucial for many practical applications such as designing electronic devices and understanding the properties of materials.

What are bound charges?

Bound charges are charges that are not free to move within a material. They are caused by the displacement of electrons within the material in response to an external electric field, and they contribute to the overall electric field within the material.

How does Griffith's ED Chapter 4 Clarification differ from free charges?

Griffith's ED Chapter 4 Clarification differs from free charges in that bound charges are not free to move, while free charges can move freely within a material. Bound charges are also caused by the displacement of electrons within the material, whereas free charges are caused by the presence of external charges.

What are some practical applications of understanding Griffith's ED Chapter 4 Clarification?

Some practical applications of understanding Griffith's ED Chapter 4 Clarification include designing electronic devices, understanding the properties of materials such as dielectrics, and predicting the behavior of electromagnetic fields in various materials.

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