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

Magnetic Flux through a solenoid

  • #1

Homework Statement



The magnetic field inside a cylindrical solenoid of area 4 cm^2 is 0.15 T along the axis of the solenoid. What is the magnetic flux through a disk of radius 3 cm placed perpendicular to the solenoid axis?

Homework Equations


[tex]\phi = \zeta B * dA [/tex]


The Attempt at a Solution



Well the area is 4 cm^2 and B is 0.15, so 6E-5 Wb is the answer, but I'm a little confused here. I thought flux for a closed surface was always 0 (gauss' law for magnetism)? What's going on here?
 

Answers and Replies

  • #2
alphysicist
Homework Helper
2,238
1

Homework Statement



The magnetic field inside a cylindrical solenoid of area 4 cm^2 is 0.15 T along the axis of the solenoid. What is the magnetic flux through a disk of radius 3 cm placed perpendicular to the solenoid axis?

Homework Equations


[tex]\phi = \zeta B * dA [/tex]


The Attempt at a Solution



Well the area is 4 cm^2 and B is 0.15, so 6E-5 Wb is the answer, but I'm a little confused here. I thought flux for a closed surface was always 0 (gauss' law for magnetism)? What's going on here?
A closed surface means that it encloses a volume. A sphere, cube, etc. would be a closed surface, but a disk would not. If you constructed a cylinder with the disk in the problem at one end, and calculated the flux through the cylinder then the flux would be zero.
 

Related Threads for: Magnetic Flux through a solenoid

  • Last Post
Replies
1
Views
6K
  • Last Post
Replies
2
Views
18K
Replies
2
Views
18K
Replies
2
Views
4K
Replies
9
Views
23K
Replies
1
Views
8K
  • Last Post
Replies
4
Views
3K
Top