Electrostatic Charging in Precipitators

Steps:

• Negative grid creates corona discharge, emitting electrons into the gas stream.
• Dust particles near the grid collide with these free electrons.
• Electrons attach to dust particles, giving them a negative charge.
• Charged particles migrate to the positive collector plate.

Why A is correct:

• In electrostatic precipitators, the negative grid ionizes dust via electron transfer, as per Coulomb's law where like charges repel and attract opposites.

Why the others are wrong:

• B: Gaining protons would positively charge particles, but the negative grid supplies electrons, not protons.
• C: Losing electrons would create positive charge, contradicting the electron-gaining process at the negative electrode.
• D: Dust particles do not lose protons; proton transfer does not occur in gas ionization.

Final answer: A