Question

Next the student brings a plexiglass rod near the pith ball. What can you conclude about the charge state of the pith ball if it has a different reaction to the plexiglass rod as it did to the PVC pipe? (10 pts)

Answer 1

The answer will depend on what was the reaction of the pith ball on the PVC and the electrical state of PVC. We assume the PVC was charged.

Suppose if it was not deflected when near the PVC, then we would assume it was neutral and might have gained some induced charge opposite to that of the PVC. This will make the pith ball charged and depending upon the charge of the plexiglass it will either get attracted (opposite charges) or repelled (same charges). Hence, if it didn't interacted with the PVC but with the plexiglass, then we would assume it was electrically neutral initially.

If the pith ball was charged, then it might have either got attracted or repelled by the PVC. Then depending on what was the action on PVC it will do the opposite with the plexiglass. This means it was either positively or negatively charged initially which made it get attracted or repelled by the PVC. We would then have the following possibilities

PVC	ACTION	PLEXIGLASS	ACTION	PITH BALL
+	ATTRACTED	-	REPELLED	-
-	ATTRACTED	+	REPELLED	+

+ and - denotes positive and negatively charged.