Induced Polarization of Conductor in Uniform Field

Steps:

• Uniform electric field E exerts force on free electrons in uncharged copper rod, causing them to drift opposite to E's direction.
• Electrons accumulate at the end facing against E, making it negatively charged; positive charges (ions) left behind at the opposite end.
• This separation creates an internal field opposing E, zeroing the net field inside the conductor.
• Result: rod ends with opposite induced charges, negative at E's "incoming" side, positive at "outgoing" side.

Why D is correct:

• Diagram D shows negative charge at the end opposite E's direction and positive at the end aligned with E, per electrostatic induction in conductors (internal E=0).

Why the others are wrong:

• A: Shows uniform charge distribution, ignoring polarization.
• B: Depicts charges perpendicular to rod, irrelevant for parallel alignment.
• C: Reverses charge signs, contradicting electron drift opposite to E.

Final answer: D