<p>A solid sphere of copper is given a negative charge. Discuss the electric field inside and outside the sphere.
Answer: the excess electrons will move quickly to the outer surface; the electric field inside will be zero.</p>
<p>But what if a positive charge was given to the sphere of copper?</p>
<p>im using PR here, but usually we discuss electric fileds with electrons. im pretty sure u wont see a positive charge insdie the sphere. check with other though. Can anyone recommend methods they used to score 700+ in phyiscs? I did the first PR practice test and just gave up because I was unsure of and omitting too many questions… and the test is in like a month. help!</p>
<p>If a positive charge was given to the sphere, that means electrons were taken away from the sphere, since protons aren’t capable of moving (unless they undergo nuclear reaction). Therefore, nothing would really happen except perhaps the remaining electrons would distribute themselves evenly across the surface of the sphere if they weren’t already. The electric field inside the sphere would still be zero because there is never an electric field inside a conducting sphere.</p>
<p>Now I’m confused with the concept of polarization. Wouldn’t introducing a positive charge to a conductor cause the negative charges of the conductor to move to the surface?</p>
<p>Yes it would. What’s not to understand?</p>
<p>Well, in polarization, if you introduce a negative charge, the positive charges will move close to the negatively charged material. But, like my answer in the first post says, the excess electrons will be moving to the surface.
And, if you introduce a positive charge, in polarization, the negative charges will move to the surface. But you said nothing will happen because the positive charges can’t move, or something like that lol.</p>
<p>Well first of all, if you have a sphere and you bring a negative object near one side of the sphere, then all of the electrons will be repelled to the other side of the sphere, leaving a positive charge on one side (the side with the negative object near it) and negative charge on the other (since all the electrons are over there now).
If you introduce a positive object to one side of the sphere, the opposite happens, meaning that the electrons are all attracted to the side of the sphere where the positive object is which leaves a positive charge on the opposite side of where the positive object is (since all the electrons are gone) and negative charge on the side where the object is (since all the electrons are over there). Hopefully that makes sense haha.</p>
<p>Yes it does, but you’re not understanding my confusion.</p>
<p>What you described is polarization. I’m saying how come the opposite happens when you introduce a negative charge to a conductor…why do the electrons in a conductor move toward the negative object?</p>