Fuse wires

  • Thread starter Vagrant
  • Start date
  • #1
Vagrant
196
1

Homework Statement



does the length of the fuse wire influence its cpacity? why?

Homework Equations



R=pL/a

The Attempt at a Solution


My teacher said no. I think it should because R depends on L


Thanks for your time.
 

Answers and Replies

  • #2
Andrew Mason
Science Advisor
Homework Helper
7,736
437

Homework Statement



does the length of the fuse wire influence its cpacity? why?

Homework Equations



R=pL/a

The Attempt at a Solution


My teacher said no. I think it should because R depends on L


Thanks for your time.
I think I would agree with your teacher. The fuse capacity (the largest current permitted to flow) depends on the temperature of the fuse wire. At a certain temperature, it melts and stops the current. Off hand, I would say that the temperature depends upon the power density being dissipated in the fuse wire (power / unit volume). The power dissipated is [itex]I^2R = I^2\rho L/A [/itex]

Now, the power per unit volume is:

[tex]P/Vol = P/LA = I^2\rho L/A(LA) = I^2\rho/A^2[/tex]

So it appears to me that the L falls out and the temperature depends entirely upon the cross sectional area of the fuse wire.

AM
 
  • #3
Vagrant
196
1
Thanks. I think your answer makes sense.
 

Suggested for: Fuse wires

  • Last Post
Replies
4
Views
1K
Replies
2
Views
556
Replies
3
Views
434
  • Last Post
Replies
3
Views
879
Replies
5
Views
471
Replies
43
Views
2K
  • Last Post
Replies
4
Views
422
Replies
4
Views
406
Replies
30
Views
602
  • Last Post
Replies
12
Views
393
Top