Question

An electrically isolated hollow (initially uncharged), conducting sphere has a small positively charged ball suspended by an insulating rod from its inside surface, see diagram.
This causes the inner surface of the sphere to become negatively charged. When the ball is centred in the sphere the electric field outside the conducting sphere is

• A. zero
• B. the same as if the sphere wasn't there
• C. twice what it would be if the sphere wasn't there
• D. equal in magnitude but opposite in direction to what uld be if the sphere wasn't there

Answer 1

The correct option is A zero

Hollow (initially uncharged)

When the ball is centered in the sphere the electric field outside the conducting sphere is zero. Because, in the equipotential surface inside the sphere the ball is electric field $+C$