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Mistake Master · AP Physics C: E&M · Unit 10 · Step-Through Animation

The Hole Is Not the Metal

You'll learnwhere "zero field inside a conductor" really applies, what a metal box can and cannot hide, and why sparks start at sharp points.

A metal shell with a charge sealed inside its hollow centre. Is the field zero in there? Can anyone outside tell the charge is in it? Twelve short steps; press Next for each one.

12 STEPS · 6 QUICK CHECKS · THE HOLE IS NOT THE METAL · ONE-WAY SHIELD · v2

zero field in the metal only · the shield only works one way
Before you start
What you're looking at
A metal shell in cross-section: the grey ring is metal, the hole is a cavity, and a small pink disc is a positive charge. Green arrows are the electric field.
The question
Where exactly is the field zero, and what can the metal really shield?
Step 1 / 12