0
$\begingroup$

Given the following system, where the conductors (marked as yellow in the picture) have spherical symmetry. The inner conductor has $\textit{+Q}$ charge and the outer conductor has $\textit{-Q}$ charge. Between both conductors, the space is half filled with a linear, homogeneous dielectric with $\epsilon = 2\epsilon_0$ and air, $\epsilon_0$, in the upper part, as can be seen in the picture. enter image description here

What is the distribution of surface charge of the inner conductor?

I named the density of surface charge in the upper half of inner sphere, $\sigma_0$, and the density of surface charge in the lower half $\sigma_1$.

I get the following equations: \begin{equation} \left( \sigma_0 + \sigma_1 \right) = \frac{Q}{4\pi a^2} \end{equation}

\begin{equation} \sigma_0 = \sigma_1 \frac{\epsilon_0}{\epsilon} \end{equation}

and so I get \begin{equation} \sigma_1 = \frac{\epsilon_0}{\epsilon_0 + \epsilon_1} \frac{Q}{4 \pi a^2} \hspace{1cm} \sigma_0 = \frac{\epsilon_1}{\epsilon_0 + \epsilon_1} \frac{Q}{4 \pi a^2} \end{equation}

Are these equations right?

$\endgroup$

1 Answer 1

1
$\begingroup$

For the first equation, you should consider the surface area of a hemisphere as the charge only charge densities are for each hemisphere independently.

The second equation stems from considering the conservation of the parallel components of the electric fields at interfaces.

I would check your results again.

$\endgroup$
4
  • $\begingroup$ Please note that answering "check my work" problems is contrary to the spirit and "rules" of this forum, although I don't blame you is you say "Oh yeah? Where does it say that?" I've complained to the moderators more than once about clear instructions about answering are hard or impossible to find in the help system. Please edit your answer to provide general guidance (or delete the answer). This is more for future readers than the current OP, who has probably already read this. $\endgroup$
    – garyp
    Commented Jun 24, 2021 at 23:20
  • $\begingroup$ Apologies and thank you for the guidance, I'm quite new here! $\endgroup$
    – Chris Long
    Commented Jun 24, 2021 at 23:22
  • $\begingroup$ Is this more appropriate? $\endgroup$
    – Chris Long
    Commented Jun 24, 2021 at 23:28
  • $\begingroup$ Bravo, and thank you. $\endgroup$
    – garyp
    Commented Jun 25, 2021 at 2:05

Not the answer you're looking for? Browse other questions tagged or ask your own question.