A dielectric hemisphere

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Homework Help Overview

The problem involves a dielectric hemisphere placed on an infinite conducting plane within a constant electric field. Participants are tasked with finding the surface charge distribution on the plane as a function of distance and exploring the implications of the dielectric properties on the system.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants discuss the implications of the dielectric constant, questioning what happens when k equals 1, and whether there would be any charge on the plane. There is also consideration of the electric field behavior within the dielectric and the potential presence of charge inside the hemisphere.

Discussion Status

The discussion is ongoing, with participants exploring different interpretations of the problem. Some have suggested using Gauss's Law and relating the problem to similar scenarios, while others are seeking clarification on the coordinate system and the implications of the dielectric constant.

Contextual Notes

There are questions regarding the definition of the variable r and the assumptions about the dielectric constant, particularly in the case where k equals 1. Participants are also considering the boundary conditions imposed by the conducting plane.

sentinel
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Homework Statement


we put a dielectric hemishphere with radius (a) and dielectric coeeficient(k) on an infinite conducting plane.the system(hemsiphere and the plane) are in a constant electric field E0.
find the surface charge distrubution on the plane as a function of (r).
and explain what happens?

Homework Equations


E in =1/k E (in a dielectric E weakens)
maxwell equations
e0E=surface charge(charge per area)

The Attempt at a Solution


for the case k=1 there won't be any charge on the plane(I think)
also I tried to think what actually happens?will there be any charge inside the hemisphere?
and these are (I think) the solutions:
}{r})^2&space;\;&space;\;&space;\;&space;\;&space;r&space;\geq&space;a&space;\end{matrix}\right..gif
 
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sentinel said:

Homework Statement


we put a dielectric hemisphere with radius (a) and dielectric coefficient(k) on an infinite conducting plane.the system(hemisphere and the plane) are in a constant electric field E0.
find the surface charge distribution on the plane as a function of (r).
and explain what happens?
What coordinate is r ?

Homework Equations


E in =1/k E (in a dielectric E weakens)
Maxwell's equations
e0E=surface charge(charge per area)

The Attempt at a Solution


for the case k=1 there won't be any charge on the plane(I think)
There is a charge on the plane, if the electric field is perpendicular to the plane.

Use Gauss's Law.

also I tried to think what actually happens?will there be any charge inside the hemisphere?
and these are (I think) the solutions:
a}{r})^2&space;\;&space;\;&space;\;&space;\;&space;r&space;\geq&space;a&space;\end{matrix}\right.gif
 
sentinel said:

The Attempt at a Solution


for the case k=1 there won't be any charge on the plane(I think)
also I tried to think what actually happens?will there be any charge inside the hemisphere?
and these are (I think) the solutions:
a}{r})^2&space;\;&space;\;&space;\;&space;\;&space;r&space;\geq&space;a&space;\end{matrix}\right.gif

Shouldn't k = 1 correspond to a vacuum (i.e., no hemisphere present)? Then the field should just equal Eo everywhere.

I don't know your background, but you can solve this problem as a boundary value problem for the electric potential. Then use the potential to get the field at the surface of the plane, and hence the charge density.

You can also relate this problem to the problem of a dielectric sphere placed in an external uniform field with no conducting plane.
 

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