A fuse in an electric circuit is a wire that is designed to melt, and thereby open the circuit, if the current exceeds a predetermined value. Suppose that the material to be used in a fuse melts when the current density rises to 500 A/cm2. What diameter of cylindrical wire should be used to make a fuse that will limit the current to 0.64 A?

Respuesta :

Answer:

The diameter of wire should be [tex]4.04 \times 10^{-4}[/tex] m

Explanation:

Given:

Current density [tex]J = 500 \times 10^{4}[/tex] [tex]\frac{A}{m^{2} }[/tex]

Current [tex]I = 0.64[/tex] A

From the formula of current density,

  [tex]J = \frac{I}{A}[/tex]

Where [tex]A =[/tex] area of cylindrical wire = [tex]\pi r^{2}[/tex]

  [tex]\pi r^{2} = \frac{I}{J}[/tex]

  [tex]r^{2} = \frac{I}{\pi J }[/tex]

   [tex]r = \sqrt{\frac{0.64}{3.14 \times 500 \times 10^{4} } }[/tex]

   [tex]r = 2.02 \times 10^{-4}[/tex]m

For finding the diameter of wire,

   [tex]d = 2r[/tex]

   [tex]d = 4.04 \times 10^{-4}[/tex]m

Therefore, the diameter of wire should be [tex]4.04 \times 10^{-4}[/tex] m