Hi Candidate,

The current density vector "j" is the vector whose magnitude is the electric current density, and whose direction is the same as the motion of the positive charges. The current density is the amount of charge per unit time.

The term "E" refers to the Electric Field which is experienced due to the movement of charges in an conductor. The term of magnitude of JE divided by E, refers to J as- I J.E I/ IEI and is equivalent to "j".

Hope that this answer helps you. Have a Good Day!!