• Support PF! Buy your school textbooks, materials and every day products Here!

Fuse wires

  • Thread starter Vagrant
  • Start date
193
1
1. Homework Statement

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

2. Homework Equations

R=pL/a

3. 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

Andrew Mason
Science Advisor
Homework Helper
7,542
318
1. Homework Statement

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

2. Homework Equations

R=pL/a

3. 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
 
193
1
Thanks. I think your answer makes sense.
 

Related Threads for: Fuse wires

  • Last Post
Replies
0
Views
2K
Replies
2
Views
4K
  • Last Post
Replies
2
Views
7K
  • Last Post
Replies
4
Views
584
  • Last Post
Replies
1
Views
9K
  • Last Post
2
Replies
27
Views
14K
  • Last Post
Replies
1
Views
994
Top