The charged particles whose flow in a exact direction constitutes the electric current are known as current carriers. In separate positions current carriers are dissimilar.
(i) Solids: In metal conductors current carriers are free electrons.
(ii)Liquids: In liquids current goes are positive and negative ions.
(iii) Gases: In gases current takes are positive ions and free electrons.
(iv) Semi conductor: In semi conductors current engage are holes and free electrons.