Charges (physics)

Question

A student tests three objects, A, B, and C, for electrical interactions. Object A is repelled by a glass rod that has been rubbed with silk. Object B attracts small bits of paper. Object C attracts both objects A and B. What can be said about the charge state of objects A, B, and C? What is the charge on object B? What is the charge for object C? What is the charge for object A?

Choose from the choices below!

(a) must have the same charge as the glass rod.

(b) must have the opposite charge as the glass rod.

(c) must be charged, but could have either the same or the opposite charge as the glass rod.

(d) must be neutral. (e) could either be neutral or have the same charge as the glass rod.

(f) could either be neutral or have the opposite charge as the glass rod.

Answer 1

I believe for this question you are supposed to assume that A, B, C are solid insulators.

I am assuming that in my answers.

"Object A is repelled by the glass rod"

implies that object A is charged same as the glass rod.

"Object B attracts small pieces of paper"

implies that object B is charged, without saying whether the charge is positive or negative.

"Object C attracts both objects A and B"

implies that A and B are charged with the same polarity,

and that C is charged with the opposite polarity.

Therefore A and B are charged same as the glass rod, while

C has the opposite charge.