Question

What is the atomic charge and current density of an electron flying along the (1, -1, 0) direction, starting at (0, 0, 0) at t=0sec.

Answer 1

The atomic charge of a moving electron is same as that of the charge of an electron at rest and also it doesn't depend on direction of flow. Hence the atomic charge of the electron moving in the given direction is .

Macroscopically, the current density (J) is defined as the electric current (I) flowing per unit area (A)of a conductor.

Current is defined as the rate of change of charge with time.

In general, the term 'current density' is used when there are a number of electron is passing through some area in a conductor. But here, we have only one electron which is moving in a direction (1,-1,0) from (0,0,0). We can use the microscopic definition of current density at any location of space which is written as

Where, 'n' is the numver of electron, 'q' is the charge of electron and 'v' is the velocity of electron.

In this case, n=1, Hence, current density in the given direction is   .

Here, and