Question: Is it possible tomake a magnet in the form of a hollow sphere where the north is the outside and south is inside?

Kamal Bhattacharya answered on 17 Jan 2017:

Awesome question. And yet I will give you my guess. The answer should be no as the total magnetic flux on a closed surface are zero. This is the Gauss Law of Magnetism or second Maxwell equation. If you image little 2-d squares over the entire sphere then the exact same number of magnetic field lines enter and exit the surface. When you sum them all up, they cancel each out other and leaves you with zero magnetic flux through the entire surface. So there can never be a charge inside. You can apply the same concept to electric current. The law the says that the net flux of current on a closed surface is zero. You may have heard this as something called the Faraday cage. So here is why this can save your life: if you are in a car and you’re driving through a thunderstorm with lightning, the best thing you can do is to never leave the car. A car is essentially a closed surface and if lightning strikes, there will be net zero flux on the closed surface of your car and you’ll never feel anything inside.
I admit it’s one of those questions that I love but I have never been able to explain the Maxwell Equations in laymen terms. But hope this helps anyway.