Question

During a classroom investigation, students place small pieces of tissue on a table and gently touch them with three different rods that were each given the same electric charge.

a copper rod
a glass rod
a plastic rod
The tissue pieces jump toward the copper rod but barely move toward the glass or plastic rods.



Which statement BEST explains why the tissue reacts differently to the rods?



A.
Both the glass and plastic rods are insulators, but only the copper rod gained a positive charge.

B.
The copper rod is a conductor, so charges can move and create a strong attractive force.

C.
The glass rod is a conductor, so its charges spread out and push the tissue away.

D.
All three rods are insulators, so charges cannot move freely.

Answer 1

B

The copper rod is a conductor, so its free charges can move and redistribute when the rod is brought near the neutral tissue. That redistribution produces a strong induced opposite charge on the near side of the tissue and a stronger attractive force. Glass and plastic are insulators, so their charges are fixed and produce much weaker induction and attraction.