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

Copper is a conductor, so its free charges can move and redistribute to produce a strong electric field and induce opposite charge on the nearby tissue. Glass and plastic are insulators; their charges are fixed and produce much weaker polarization/attraction of the tissue.