What it shows:
A lecturer's faith in the principle that an electric field cannot exist inside a charged conductor is put to the test using a Faraday cage that is large enough to sit in.
How it works:
The lecturer (or some volunteer) climbs the three steps and sits upon a plain wooden chair. Their assistant pulls the mesh door closed and fastens it. A Van de Graaff, whose dome is in contact with the cage, begins to charge itself and the cage up to a high voltage. The person inside is oblivious to the large amount of charge now residing on the outside of the cage, that is until the assistant starts drawing long sparks off it using a grounded sphere. The sparks (whose length depends upon the type of day it is) can even be pulled right from the tip of the occupant's nose when pressed against the wire mesh!
The cylindrical cage has the dimensions shown in figure 1. It is made of a coarse brass mesh (5mm square holes), with the door simply an overlap in the mesh sheet that is wrapped and held closed with a rubber tube catch. The floor and ceiling are reinforced using discs of plywood (overlaid with the brass) and four steel conduit tube pillars inside the cage make it rigid.
figure 1. The walk-in Faraday Cage.
Setting it up:
The cage sits atop a stepped platform, that not only adds to the pathos but also insulates the cage from ground. The Van de Graaff dome presses against the side of the cage. For ease of movement, the platform is on wheels, and the cage itself has a custom built dolly. Rubber tube handle grips threaded through the mesh make it easy to lift the cage.
Shows well the idea that the safest place to be in a thunderstorm is inside your car (unless your car is a Corvette, because they're plastic!)