# Why is the Electric Field Zero Inside a Spherical Conductor?

With the introduction of the electric field in introductory physics courses, the first thing is a calculation of the electric field due to a point charge. But who has actually seen a point charge? I mean, sure — an electron would be a point charge, but you can’t really see it.

Most textbooks go on to introduce macroscopic objects like a solid metal (conducting) sphere with excess electric charges. With a conducting sphere, the following should be true:

• Extra electric charge will be uniformly spread on the surface of the sphere (in the absence of an external electric field).
• The net electric field inside the conductor will be zero (zero vector).
• The electric field outside the conductor has the same value as a point charge with the total excess charge as the conductor located at the center of the sphere.

OK, I’m going to skip the first point and just assume that it’s true (but here is a super great post showing how free charges end up on the surface — I would like to reproduce these calculations in python).

But what about the other two points? How do you show that the electric field inside the conductor is zero? What about outside? Here’s what I’m going to do. I’m going to model a spherical conductor with 2000 point…

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Physics faculty, science blogger of all things geek. Technical Consultant for CBS MacGyver and MythBusters. WIRED blogger.