A charged paint is spread in a very thin uniform layer over the surface of a plastic sphere of diameter 12.0 cm, giving it a charge of −49.0 μ C. Find the electric field (a) just inside the paint layer;

Video transcript

Welcome back everybody. We are taking a look at a conducting solid sphere. We are told that it has a radius of 10 cm and we are told that when the sphere is rubbed with a positive rod it acquires a charge And this charge is Micro columns. We are tasked with finding what the magnitude of the electric field is at a point right inside of the sphere which I will label as point A. Now according to God's law, we know that the electric flux is equal to the magnitude of the electric field times the surface area of the sphere. So since it's a sphere, it's just gonna be four pi R squared. We also know that the flux is equal to the charge enclosed divided by the electric Perma titty constant. So I'm gonna divide both sides by four pi R squared. And this these terms will cancel out. And we get that are electric field is equal to this entire term here. Now we have almost everything in this term. But what is you in closed Well, let me paint a picture this way at this point. A We now have a new smaller radius which I will label R. A. Now with this smaller radius, we're going to have a sphere on the inside, that kind of looks like this. Now keep in mind that the surface of the sphere has this charge, right? Nothing on the inside of that sphere has that charge. Therefore at this new sphere which is smaller than our original sphere, the n charged clo uh sorry the enclosed charge is simply zero, meaning that our electric field at that point will also be zero, corresponding to our answer. Choice of a thank you all so much for watching. Hope this video helped. We will see you all in the next one.