Confusion in electric field inside a conductor

conductorselectric-fieldselectrostatics

Image I'm referring to:

![enter image description here

In the figure both shells are conductors.

Let's say I have to find the electric field at a point P as shown in the figure. I thought, since this point lies inside a conductor, the Electric field at this point has to be $0$ no matter what. But I was taught that there will be no electric field at P due to the outer shell but there will be a electric field at point P due to the inner shell, (because it has some charge).

I'm confused now, beacuse earlier I was told the electric field inside a conductor is $0$, and that point clearly lies inside the conductor, where am I going wrong? Won't there be induction of $-Q_{1}$ on the inner surface of the outer shell, in such a way that the electric field inside the conductor becomes $0$?

Also, by the term inside the conductor mean in the bulk or in the material of the conductor or something else?

Please help me out, I have studied from many sources, any no one cares to be critical about their words, hence the confusion.

Edit: For all future readers, this image is a good explaination of what is going on inside such situations.
![enter image description here

Best Answer

The most reliable way to approach these problems is to use fundamental laws of electromagnetism, in particular Gauss' law and linearity of the electric field. A thorough application of these laws can answer all of your questions.

Gauss law

The electric field flux through a closed surface $\Phi_E$ is given by the charge inside that surface $Q_{int}$ divided by $\varepsilon_0$: $$\Phi_E = \frac{Q_{int}}{\varepsilon_0 }. $$

Linearity of electric field

The total electric field at a point is the vector sum of all the electric field produced by the single sources. If there are two sources labeled $1$ and $2$, the field at a point $\vec{E}(P)$ is

$$ \vec{E}(P) = \vec{E}_1(P) + \vec{E}_2(P). $$

Let's now use these tools to solve your problem: at point P there are in principle two contributions to the field, one coming from the inner shell, and one coming from the outer shell. The former has modulus $Q_1/4\pi\varepsilon_0r^2$ and the latter vanishes, as a consequence of Gauss' law (exercise). Bottom line: there is an electric field at P, only coming from the inner shell charges.

Now let's comment your statements one by one:

I thought, since this point lies inside a conductor, the Electric field at this point has to be 0 no matter what.

This is a misunderstanding, since "inside a conductor" means "in the bulk" of a conductor, but here there's no bulk at all.

I was taught that there will be no electric field at P due to the outer shell but there will be a electric field at point P due to the inner shell

This is correct, as discussed above.

EDIT while writing this answer, I was unaware of most of the comments and other answers, so there might be some redundancy.

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