JEE Main Syllabus 2025 PDF - Subject Wise Topics

# Current Density - Practice Questions & MCQ

Edited By admin | Updated on Sep 18, 2023 18:34 AM | #JEE Main

## Quick Facts

• Current Density is considered one of the most asked concept.

• 4 Questions around this concept.

## Concepts Covered - 1

Current Density
1.  Current density

• Current density: The amount of electric current flowing per unit cross-sectional area of a material.

• It is a vector quantity.

If a current of $\Delta i$ flows through an area $\Delta A$ the  average current density $\overline j=\frac{\Delta i}{\Delta A}$ in the direction of current

At point P :

$j=\lim_{\Delta A\rightarrow 0}\frac{\Delta i}{\Delta A}$   in the direction of current

1. If current not Perpendicular to Area

$J_{av}=\frac{di}{dA \cos\theta}$

$di=JdA \cos\theta=\vec{J}\cdot d\vec{A}$

$\theta$ is the angle between the normal to the area and direction of current

• If the current density $\vec{J}$  is uniform for a normal cross-section $\vec{A}$ then

$i=\int \vec{J}.d\vec{A}$

• Unit and dimension -

Unit of current density is $Amp/m^2$

DImension of current density is  $[L^{-2}A]$

## Study it with Videos

Current Density

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