Gauss's Law Sphere 5B20.34

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This demonstration is used to prove semi-quantitatively that the charge on a charged, hollow conductor resides on the outside.

The hollow Gauss's law sphere and the 1000V DC power supply are in the [:ElectrostaticsCabinet:Electrostatics Cabinet], B2.

The Faraday cage and the electrometer are in the [:ElectrostaticsCabinet:Electrostatics Cabinet], B1.

The proof plane is in the [:ElectrostaticsCabinet:Electrostatics Cabinet], A1.

Connect the electrometer to the Faraday cage, grounding the outside cage, and making sure the leads are twisted (in order to minimize spurious deflections of the electrometer).

Set the electrometer to half-scale zero, and 10V.

Connect the 1000V terminal of the power supply to the inside of the Gauss's law sphere, as shown (yellow cable in picture). There is no connector inside the sphere, the end of the cable rests against the sphere.

Make sure the cable hugs the edge of the opening in the sphere, so that there is room to get the proof plane in and out without touching the cable or the sphere.

Ground the proof plane and yourself (this may be the most challenging part of the experiment). You know that you are sufficiently grounded when you can insert the proof plane inside the inner Faraday cage, and remove it again, without causing the needle to deflect.

Insert the proof plane inside the sphere and touch it to the inside, without touching it to the lip (the lip has a non-zero charge density).

Remove the proof plane from the sphere without touching the sphere or the cable (touching it to either can cause it to charge up, either by direct conduction from the sphere or by rubbing against the cable).

Insert the proof plane inside the central Faraday cage. The needle should not deflect!

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