Recent content by andrea96

If in the problem you have just posted, you disconnect the spher and you add a point charge q1 outdide, the field inside the cavity don't change... are you agree?

Excuse me I haven't understood... however kq/a^2 is just the field dues by the internal point charge, but the distribution on the inner surface dues a non-zero field because the shift of q from the center changes the distribution on the inner sufrace than the -q charge on the inner surface isn't...

Really I think the distribution on the inner surface doesn't depend on what happen on the outer surface and out of the spher: in fact I could divided the sphere with a circle line in the middle of the outer and inner surface without changing somethig and so I' d create two cincentric conductors...

For the net field is it possible that the answer is E=\frac {kq (R^3-a^3)}{a^2R^3} ?

Thank you very much!

Thanks for your answer! However my expression for E doesn't satisfy Maxwell equation because, as I said in one of my initials post, it isn't the vectorial electric field, but just his component along the tangential direction. However I understand what you are saying about the unicity of the...

Maybe I have explained vary bad: I used the EMF to calculate the E field, the result about EMF isn't a paradox (it obviously depend on r), but the result of E filed constitutes a paradox. I try to explain better: in the space there is a uniform infinitely extended B field that is changing in...

Perfect! This is the paradox: I can obtain infinity different results for each direction of the electric field. You have said that the explanation of this paradox is the impossibility to creat that magnetic field: this could be an interesting answer, but I'd like to inivite you to think that...

Excuse me I haven't explained very well: the circuitation certenly depend on r, because it is a "propety" of the circle... but the electric field cannot depend on r because it cannot depend on the choise of a particular circle instead of an other! In fact electric field is a "property" of the...

if there is an uniform, infinitly extended,magnetic field that is changing with a law B(t), I can calculte the induced electric field using an arbitrary circle; then the induced circuitation on the circle is \epsilon _i=-\pi r^2 \frac{dB(t)}{dt} , and since the symmetry of the system ( infact...