II. Macroscopic polarization A large slab of plastic is placed inside a uniform,
ID: 1771095 • Letter: I
Question
II. Macroscopic polarization A large slab of plastic is placed inside a uniform, external electric field. The slab is large enough that fringing fields can be ignored A. Suppose the atoms in the plastic have not polarized yet. Plastic Slab In what direction is the net force on an electron cloud near the center of the slab? B. Consider the following student discussion about the macroscopic effects of polarization: Student 1: The electric field pushes positive charge upward and negative charge downward so the top half of the slab will all be positively charged and the bottom half will all be negatively charged. "I disagree. The downward displacement of the electrons in one atom will be compensated by the displacement of the electrons in the atom above. The atoms will all remain net neutral, so the slab will be net neutral everywhere." Student 2: Do you agree with either student? If not, where on the slab is there a non-zero net charge? The charged regions caused by this polarization are called bound chargesExplanation / Answer
I agree with the student I but not with student II. The displacement caused due to the Electric field can't be compensated. The free electrons will be pushed to the down of the slab and the lower slab become negatively charged whereas the upper slab becomes positively charged as stated by the student I.