| Directions : (1-5) |
| Electric Current and Current Density |
| The flow of charge in a particular direction constitutes the electric current. Current is measured in Ampere. |
| Quantitatively, electric current in a conductor across an area held perpendicular to the direction of flow of charge is defined as the amount of charge flowing across that area per unit time. |
| Current density at a point in a conductor is the ratio of the current at that point in the conductor to the area of cross section of the conductor of that point. |
| The given figure shows a steady current flows in a metallic conductor of non-uniform cross section. Current density depends inversely on area so here \[{{J}_{1}}>{{J}_{2}}\] as \[{{A}_{1}}<{{A}_{2}}\] |
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A) \[2.5\,\,\times {{10}^{-10}}A\]
B) \[1.6\times {{10}^{-10}}A\]
C) \[7.5\times {{10}^{-9}}A\]
D) \[8.2\times {{10}^{-11}}A\]
Correct Answer: B
Solution :
\[q={{10}^{6}}\times 1.6\times {{10}^{-19}}C=1.6\times {{10}^{-13C}}\] \[t={{10}^{-3}}s\] \[I=\frac{q}{t}=\frac{1.6\times {{10}^{-13}}}{{{10}^{-3}}}=1.6\times {{10}^{-10}}A\]
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