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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]

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Current Density

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