Why do the free electrons in a metal wire, flowing by themselves, not cause any current flow in the wire

A current flows in a wire of circular cross section with the free electrons travelling with drift velocity vecV . If an equal current flows in a wire of twice the radius, new drift velocity is

The magnetic field at the origin due to the current flowing in the wire is

The magnetic field at the origin due to the current flowing in the wire is

The magnetic field at the origin due to the current flowing in the wire is

A current .I. flows through a metallic wire of radius .r. and the free electrons in it drift with a velocity v_(d) . Calculate the drift velocity of the free electrons through the wire of the same material, having double the radius, when same current flows through it.

If a current of 0.5 ampere flows through a metallic wire for two hours, then how many electrons flow through the wire?

If a current of one ampere flows through a metal wire for one hour, how many electrons would flow through the wire?