Calculating diamter of wire that will blow if current exceeds 1A

[Linus Pauling]

Calculating diamter of wire that will "blow" if current exceeds 1A

1. You need to design a 1.0 A fuse that "blows" if the current exceeds 1.0 A. The fuse material in your stockroom melts at a current density of 500A/cm^2.



2. J = I/A



3. J = 500A/m^2 = 50000A/m^2 = 1.0A / (pi*r^2)

r = sqrt[1/50000*pi] = 0.00252 m
diamter = 2*r = 0.005 m = 5.0mm

That is incorrect (answer in mm).

 

[tiny-tim]

1. You need to design a 1.0 A fuse that "blows" if the current exceeds 1.0 A. The fuse material in your stockroom melts at a current density of 500A/cm^2.
…
3. J = 500A/m^2 = 50000A/m^2

Hi Linus Pauling!

(try using the X² tag just above the Reply box )

You didn't use enough zeros to convert from cm² to m²

(but why bother? why not leave it as cm??)

 

[Linus Pauling]

ahh cripes. thanks for the catch... i always do that. :)