What is Current density?

Current density (J) is a measure of the electric current (flow of charge) per unit area of cross-section through which the current flows. It informs about how densely the current is distributed in an area.

Formula

The formula for current density is:

Where:

• J is the current density (A/m²)

• I is  electric current (in amperes, A)

• A is  cross-sectional area (m²)

Solved Problems

Problem 1: A 5 mm² copper wire carries a current of 5 mA of current. Calculate the current density.

Solution:

Given:

Total Current I = 5 mA

Total Area A = 5 mm²

The Current density is,

  = 1 A/ m²

Problem 2: A copper wire has a current flowing through it is 3 A and cross-sectional area of  0.0001m². Calculate the current density.

Solution:

Given: 

I = 3A

A= 0.0001m²

Therefore the current density is 30000 A/m².

Conclusion

Thus, current density is fundamentally used to describe how electrical currents distribute within and between different materials and applications. It also plays an essential role in optimizing designs and performance in electrical and electronic systems.

 

Other Related Sections

NCERT Solutions | Sample Papers | CBSE SYLLABUS| Calculators | Converters | Stories For Kids | Poems for kids| Learning Concepts I Practice Worksheets I Formulas | Blogs | Parent Resource