Question

A wire of ${10}^{-3}c{m}^2$ cross sectional area carries a current of 0.25 A, then current density is

• A. $1.5\times {10}^{6}A{m}^{-2}$
• B. $2.5\times {10}^{6}A{m}^{-2}$
• C. $3.5\times {10}^{6}A{m}^{-2}$
• D. $4.5\times {10}^{6}A{m}^{-2}$

Answer 1

The correct option is B

$2.5\times {10}^{6}A{m}^{-2}$

$J=\frac{I}{A}=\frac{0.25}{{10}^{-3}\times {10}^{-4}}=2.5\times {10}^6{A}^{-2}$