The measure of the amount of electric charge per unit time that flows through the unit area of the cross-section. The Current density is a vector quantity. Therefore, it has both magnitude and direction. The S.I unit of Current density is A/m2 and is denoted by the symbol J.
Current Density
Formula of Current Density
Current Density Formula is expressed as,
J = I / A
Where,
- I denote the current flowing through the conductor in Amperes
- A denotes the cross-section area in m2
- Current density is expressed in A/m2
Solved Examples
Example 1
A 5 mm2 copper wire has a current of 5 mA of current flowing through it. Determine the current density.
Solution
Given:
Total Current I is 5 mA
Total Area A is 5 mm2
The Current density J = I / A
= 5×10−3 / 5×10−3
= 1 A/m2