All Questions
6 questions
3
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480
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Second derivative of unit vector
We know that the second derivative of unit vector (the vector from a point toward the source) is proportional to the Electric field caused by the source in a particular point.
If we imagine that our ...
- 63
0
votes
1
answer
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What are some ways to derive $\left( \boldsymbol{E}\cdot \boldsymbol{E} \right) \nabla =\frac{1}{2}\nabla \boldsymbol{E}^2$?
For each of the two reference books the constant equations are as follows:
$$
\boldsymbol{E}\times \left( \nabla \times \boldsymbol{E} \right) =-\left( \boldsymbol{E}\cdot \nabla \right) \boldsymbol{E}...
- 105
0
votes
1
answer
39
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Spherical and Cartesian forms of divergence [closed]
Suppose the electric field found in some region is $$\overrightarrow{E} = ar^3\vec{e}_r$$ in coordinates
spherical (a is a constant). What is the charge density?
So, using the spherical form of ...
1
vote
1
answer
74
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Calculating the divergence of static electric field without making the dependency argument?
This question is a follow up on this old post here Divergence of electric field
(So this may seem dumb...)
When calculating the divergence of a field point through the following equation, where $\left(...
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0
votes
0
answers
38
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Why is linear approximation of contribution of electric field the same as if whole charge was concentrated at a single point?
I was reading about electric field of uniformly charged ring, of radius $R$, on the axis of the ring at the distance $d$ from the center of the ring and I am confused about usage of differentials. It ...
- 21
0
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1
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173
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The differential of a quantity
I often see the differentials of the electric field strength and the acceleration due to gravity being written as:
$$dE= \mathcal{k}\frac{dQ}{r^2} \tag{1}$$
and
$$dg=\frac{GdM}{r^2} \tag{2}$$
...
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