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Current Electricity — Physics STD 12 Science — Question

Gujarat BoardEnglish MediumSTD 12 SciencePhysicsCurrent Electricity1 Mark
Question
Define current density. State its unit.
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Answer

Magnitude of current flowing in the perpendicular direction of unit area of cross-section is known as current density J.
Current density $J =\frac{ i }{\Delta S }$, where, $\Delta S$ is area of cross-section.
If the direction of flow of charge is inclined at an angle with the perpendicular, then
current density, $J=\frac{i}{\Delta S \cos\theta}$ or $I=\vec{J} \cdot \overrightarrow{\Delta S}$

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