Question

When a neutrally charged conductor is given a negative charge... (choose any of the methods by which this is physically accomplished)

Some electrons are created

Some protons are destroyed

Electrons are transferred from another source

Electrons are transferred to another source

Some neutrons are transformed into electrons

Some protons are transformed into electrons

None of the above

Answer 1

Electrons are transferred from another source

_{Let's assume that we're talking about macroscopic objects, say particles of soot. The neutral object (call it 'O') will attract either a positively charged object ('P') or a negatively charged object ('N'). Here's why…}

_{If P is placed near O, P will tend to pull the electrons in O towards the side of O nearest P. If O is a conductor, free electrons will move through O; if O is an insulator they will be pulled minute distances within each molecule while the nuclei are pushed minute distances away from P. The result in either case is that O will behave as a dipole with its negative charge closer to P than its positive charge. But P's electric field is stronger the closer we are to P. So P will pull the negative charge of the dipole more strongly than it repels the positive charge of the dipole. So O will experience a net attractive force towards P. And, of course, (appealing to Newton's third law) P will have a net attractive force towards O.}

_{If you go through exactly the same argument, but with N instead of P placed near O, and remembering that N's electric field will be in the opposite direction to P's, (that is N repels electrons and attracts nuclei) you'll find that N, just like P, attracts O, so O attracts N.}