Conventional direction of an electric current
When the simple cell was discovered in the year IgOO its action was not understood, and scientists had no way of finding out in which direction the current flowed. They therefore decided to adopt the convention of regarding the current as a flow of
positive electricity from the copper to the zinc. Although, as explained above, we now have good reason to believe that current is
a flow of negative electrons from zinc to copper, yet we still retain the old convention. In all direct-current, (d.c.), circuit diagrams an arrow is therefore placed on the wires to indicate that the conventional current flows from the positive terminal of a
cell towards the negative terminal.