positive ions will not give rise to current. Figure . Zig-zag motion and drift velocity v d → → This velocity is called drift velocity v d . The drift velocity is the average velocity acquired by the electrons inside the conductor when same as a transfer of negative charge in the opposite direction.
Electric current is not only produced by batteries. In nature, lightning bolt produces enormous electric current in a short time. During lightning, very high potential difference is created between the clouds and ground and hence charges flow between the clouds and ground. .
. Drift velocity In a conductor the charge carriers are free electrons. These electrons move freely through the conductor and collide repeatedly with the positive ions. If there is no electric field, the electrons move in random directions, and hence their velocities are also randomly oriented.
On an average, the number of electrons travelling in any direction will be equal to the number of electrons travelling in the opposite direction. As a result, there is no net flow of electrons in any direction and hence there will not be any current. Suppose a potential difference is set across the conductor by connecting a battery, an electric field E is created in the conductor. This electric field exerts a force on the electrons, producing a current.
The 12th - 12th - - - - - Unit CURRENT ELECTRICITY EXAMPLE . If an electric field of magnitude N C – , is applied in the copper wire, find the acceleration experienced by the electron. Solution: E = N C – , e = . × – C, m = .
× – kg and a = ? F = ma = eE a eE = . × m s – Misconception (i) There is a common misconception that the battery is the source of electrons. It is not true.
When a battery is connected