How can the electric field inside a conductor be zero?

[rude man]

"Now there is a field within the sphere due to the surface charge"

So does this mean there can be electric fields inside a hollow charged conductor?

If you put a charge inside the shell then certainly an E field exists inside the shell. E.g. put it at the center, the E field inside the shell is kq/r^2 directed everywhere away from the center. But a radioactive decay means there are +2q and -2q charges inside the shell, doesn't it? So I assume you imply that the electrons are shot away outside the shell?

 

[rude man]

"Now there is a field within the sphere due to the surface charge"

So does this mean there can be electric fields inside a hollow charged conductor?

Already here you have changed the situation. You started with a solid sphere, now it's a hollow sphere.

Bottom line: if it's solid there is no E field inside it; all the charge gets distributed evenly about its surface regardless of how much extra charge you stuff inside it. (if it's a poor conductor just give it a bit of extra time).

If it's a hollow sphere (a shell) you can put a charge inside the shell and then yes there will be a finite E field inside.

The whole discussion from this post on seems to flounder on the confusion between a solid and a hollow sphere ...

 

[swampwiz]

Well, we've just started to learn electrical fields 2 weeks ago (I am in 2nd year IB HL Physics). I don't really know what a flux is either. I was just confused about how it is possible that the textbook/teacher says "there is no electric field inside a hollow sphere". But I guess this is a topic that is too advanced for me currently, I might revisit this when I learn about more advanced stuff (maybe later in the year or in college). But thank you for answering my question.

What your instructor was saying is basically what Newton concluded early in his work on gravitation - that a radially symmetric (mass) density field has the effect of being as if it were a point mass at the center, and that the gravity field inside any particular radial distance due to the mass outside of that radial distance is zero. This applies to any inverse-square law force, which of course static electricity behaves as.