Question

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

• A. 1.5×10⁶ Am^-2
• B. 2.5×10⁶ Am^-2
• C. 3.5×10⁶ Am^-2
• D. 4.5×10⁶ Am^-2

Answer 1

The correct option is B

2.5×10⁶ Am^-2

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