Question

A metal wire of radius 0.4 mm carries a current of 2 A. Find the magnitude of current density if the current is assumed to be uniformly distributed over a cross sectional area.

Answer 1

Given: r = 0.4 mm = 0.4 × 10^-3 m, I = 2 A

To find: Current density (J)

Formula: J = \(\frac{I}{A}\)

Calculation: From formula,

J = \(\frac{2}{3.142\times(0.4)^2\times10^{-6}}\)

= 3.978 × 10⁶ A/m²