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Current Density is considered one of the most asked concept.
14 Questions around this concept.
while calculating current passing through a wire which area is taken?
A charge is flowing uniformly through a cross-section of area A. Then the current density is independent of
If current 'i' flowing through a cross-section A makes an angle $30^{\circ}$ with area vector. The current density $J$ is :
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If 25 A of current passes through a uniform solid cylinder of total surface area $150 \pi \mathrm{~cm}^2$ and height 10 cm. Find the current density
The electric field through a cross section of area $2 \mathrm{~m}^2$ makes an angle of $60^{\circ}$ with the area vector. The current through cross-section is given by
current density is
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 $\bar{j}=\frac{\Delta i}{\Delta A}$ in the direction of current
At point $P$ :
$j=\lim _{\Delta A \rightarrow 0} \frac{\Delta i}{\Delta A}$ in the direction of current
If current not Perpendicular to Area
$
\begin{aligned}
J_{a v} & =\frac{d i}{d A \cos \theta} \\
d i & =J d A \cos \theta=\vec{J} \cdot d \vec{A}
\end{aligned}
$
$\theta$ 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} \cdot d \vec{A}
$
- Unit and dimension -
Unit of current density is $A \mathrm{mp} / \mathrm{m}^2$
DImension of current density is $\left[L^{-2} A\right]$
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