Question

Electric current is the flow of particles with
(a) a negative charge.
(b) a positive charge.
(c) both positive and negative charges flowing opposite to each other.
(d) either positive or negative charge depending on the material.

Answer 1

d) either positive or negative charge depending on the material

In a solid conductor (copper wire, aluminium wire, etc.), current is the flow of negative charges (electrons). The direction of current is opposite to the direction of electrons. In a liquid conductor (a salt solution), current is the flow of positive ions (positive charges). Flow of current is the same as the direction of positive ions, but opposite to the direction of negative ions.