Charge induction by electron flow in conductors

Steps:

• Negative charge in thundercloud repels electrons in the grounded lightning conductor.
• Electrons flow downward through the conductor to the ground.
• The top of the conductor loses electrons, leaving unneutralized positive ions.
• This results in a net positive charge at the top, attracting lightning.

Why A is correct:

• In metallic conductors, electrons are the mobile charge carriers; their downward movement (as per electrostatic induction) depletes negative charge from the top, creating positive charge there.

Why the others are wrong:

• B: Protons are bound in atomic nuclei and do not move in conductors; charge transport occurs via electrons.
• C: Protons in air do not attach to the conductor; positive charge arises from electron loss, not external proton addition.
• D: Upward electron movement would add negative charge to the top, making it negative, not positive.

Final answer: A