What is thermal motion of free electrons ? Why does it not amount to any current ?

Explanation

Due to thermal energy available to free electrons in a metallic conductor they are in a continuous stage of motion in all possible random directions . Thermal speed of free electrons is of the order of `10^5m//s` . Due to the presence of a large number of free electrons in metal and all moving in all random directions so there is no net flow of charge in any specific direction. Average velocity of all the free electrons present inside the volume of the metallic conductor due to thermal motion is zero at all instants of time. Electric current requirs a net flow of charge in some direction .
Hence, thermal motion of free electrons does not contribute to electric current.