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Do electric field lines approaching a boundary at an angle get refracted and change direction just like light rays do?

Because will discussing electric field lines and flux associated with it we do not consider a change in direction

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    $\begingroup$ It's really unclear what you're asking. $\endgroup$
    – Señor O
    Commented Apr 24, 2023 at 14:21
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    $\begingroup$ I think the question is: do electric field lines approaching a boundary at an angle get refracted and change direction just like light rays do? It is a good question $\endgroup$
    – RC_23
    Commented Apr 24, 2023 at 14:25
  • $\begingroup$ We had similar questions about the conservation of field lines in dielectrics before like physics.stackexchange.com/q/643702. The important thing to understand is that physically the external field causes a polarization of the dielectric, even if the number of field lines (which are a human tool to visualize the field) is unchanged. $\endgroup$ Commented Apr 24, 2023 at 15:11
  • $\begingroup$ The electric field (and the electric field lines) will generally change across a boundary. The calculation can be performed using these boundary conditions. $\endgroup$
    – Aiden
    Commented Apr 24, 2023 at 15:35

2 Answers 2

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When light (or an EM wave) reaches an inetrface the direction of propagations changes. This is not the same as the direction of the electric field. The change in propagation direction is not related and does not imply a change in the direction of the electric field. So, the logic of the question is flawed (non sequitur). However, the electric field lines can change direction at a dielectric interface and they are shown to do so in the diagrams treating electric field in and around dielectrics. So, this part of the OP question "So why don't we consider for their direction change?" is based on a false assumption. We do. Dielectric cylinder

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  • $\begingroup$ You say that the change in direction of propagation does not not imply change in ithe direction of its component? What reasoning do you give? Please explain the reason $\endgroup$
    – Curious
    Commented Apr 24, 2023 at 16:37
  • $\begingroup$ Components of what? I said that the change in direction of propagation is not related to the direction of field lines at the boundary. They are two different things. Even longitudinal waves show refraction. Do you realize the difference between the two? The field lines change direction for static fields too. No waves there and no direction of propagation. $\endgroup$
    – nasu
    Commented Apr 25, 2023 at 1:04
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If you place a lossless dielectric ellipsoid in an uniform external field $\mathbf E_0$ the sum total $\mathbf E$ of the internally induced $\mathbf E_1$ plus external bias field, $\mathbf E = \mathbf E_0 +\mathbf E_1$ and $\mathbf D = \epsilon \mathbf E$, will be uniform inside the dielectric whose direction will depend on the direction of $\mathbf E_0$ relative to the axes of the ellipsoid.

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