MIT 8.02X: Electricity and Magnetism
Dr. Walter Lewin
Quincy's Notes

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1/5/2018
Lecture 5 - Saturn Brooch
[E=-GradV, Conductors, Electrostatic Shielding] 
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- Any hollow conductor will have zero electric field inside cavity. Consequence of Gauss's Law, just draw Gaussian surface, LoopInt(E.dl)=0
- Charges move freely in conductors (by definition)

DEMO: Show no charge inside hollow conductor. Charges metal lid by first charging insulating glass plate by rubbing with cat fur (+charged) and touching the two. Then charges paint can (-charged) and repeats. Takes test sphere and touches OUTSIDE of paint can, meaures significant charge with elestroscope. Now touches INSIDE of paint can and measures nothing with the electroscope.

- Touch on polarization of hollow conducting box in static E-field due to external positive and negative point charges. Electrostatic shielding (Faraday cage).

- What if we place a +charge inside a hollow conducting sphere? By Gauss's Law -charge gathers on inside (depending on where point charge is located. If closer to one wall then non-uniformly distributed on inside surface) of conductor to cancel +charge LoopInt(E.dA)=q/eps0. +Charge gathers uniformly on outside surface of sphere unaware of charges inside conductor.

DEMO: Place hollow conducting can in static electric field of Van de Graaff generator. -charge on 1 side of can +charge on the other, no charge inside.

DEMO: Lewin Goes in Faraday cage with radio and tinsel, turns on Van de Graaf generator to show effect of electrostatic shielding.