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

Calculating magnetic force on circular coil carrying current

  • Thread starter cseil
  • Start date
  • #1
28
0

Homework Statement


A circular coil with center on the z axis and orthogonal to the xy axis carries a current. The coil is in a magnetic field B with axial simmetry compared to the x axis. B forms an angle θ with the z axis. Calculate the magnetic force acting on the coil.

exerc.png


2. Homework Equations

$$\vec{F_B} = i \vec{dl} x \vec{B}$$

The Attempt at a Solution


[/B]
I tried considering $$ dl = r d\phi $$
So [itex]F = irB_zd\phi [/itex]
where Bz is [itex]Bcos\theta[/itex]

By is null because it has opposite verse on opposite points of the coil. So I can consider just Bz

$$ F = irBcos\theta d\phi = irBcos\theta \int_0^{2\pi} d\phi = 2\pi irBcos\theta$$

The result, according to the book, is [itex]2\pi irBsin\theta[/itex]
Why?
 

Answers and Replies

  • #2
516
63
How does your book define ##\theta##? Is it the angle the magnetic field makes with the horizontal(i.e. ##B_y##)?
 
  • #3
28
0
How does your book define ##\theta##? Is it the angle the magnetic field makes with the horizontal(i.e. ##B_y##)?
It is the angle between B and Bz!
 
  • #4
rude man
Homework Helper
Insights Author
Gold Member
7,627
714
The coil is in a magnetic field B with axial simmetry compared to the x axis.
What does this mean?
 
  • #5
28
0
What does this mean?
I can't understand what does it mean, actually.
 
  • #6
rude man
Homework Helper
Insights Author
Gold Member
7,627
714
I can't understand what does it mean, actually.
So ask! The problem is not you, it's the instructor who can't write understandably!
 

Related Threads on Calculating magnetic force on circular coil carrying current

Replies
1
Views
3K
Replies
3
Views
980
Replies
3
Views
1K
Replies
6
Views
1K
Replies
3
Views
3K
Replies
1
Views
914
Replies
42
Views
492
Replies
9
Views
416
Replies
3
Views
3K
Top