Answer to Question #340855 in Electricity and Magnetism for viraj

Question

A fuse is made of material that melts when the current density reaches 400 A cm2 . What is the diameter of the fuse wire needed to limit the current to 0.40 A? 

Answer 1

$\sigma=\frac{4I}{\pi d^2},\implies$

$d=\sqrt\frac{4I}{\pi\sigma}=0.36~mm.$