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

Find the magnetic field at a point

  • #1
251
11

Homework Statement


7_C4_B897_E-8_BAD-4246-8217-38_A002_ACAA7_D.jpg


Homework Equations


B=(μ0*I)/(2πr)

The Attempt at a Solution


B2 = (4*4*10-7)/(2*0.1)
= 8 μT
B1 = (3*4*10-7)/(2*0.1)
= 6μT
Could I know how to determine the directions ?
 

Attachments

Answers and Replies

  • #2
BvU
Science Advisor
Homework Helper
2019 Award
13,009
3,005
Know about the right-hand rule ?

The directions matter (to some extent), but
do the signs matter ? They are only asking for a magnitude ...
 
  • #3
251
11
  • #4
BvU
Science Advisor
Homework Helper
2019 Award
13,009
3,005
  • #5
251
11
So draw the arrows to find how you have to add them.
B2 = 8μT (-j) , because the direction of I2 is (-i).
B1 = 6μT (i) , because the direction of I1 is (j)
So , Bnet = √(82+62) = 10 μT ?
 
  • #6
BvU
Science Advisor
Homework Helper
2019 Award
13,009
3,005
  • #7
251
11
I'd vote for ##-\hat k## :rolleyes:
So , B2 (##-\hat j##)
B1 (##\hat i##)
 
  • #8
BvU
Science Advisor
Homework Helper
2019 Award
13,009
3,005
I agree. (I also agreed with #5, except for the directions of the currents :wink:)

I hope you now understand my frivolous 'do the signs matter': in this case just knowing that the field vectors are perpendicular is enough to get 10 ##\mu##T as answer. Normally the signs certainly do matter.

To boot a small ##\TeX## tip: Donald Knuth has provided \imath and \jmath so the hat and the dot don't pile up: ##\ \hat\imath,\ \hat\jmath ##
 

Related Threads on Find the magnetic field at a point

  • Last Post
Replies
3
Views
2K
  • Last Post
Replies
12
Views
431
Replies
9
Views
5K
Replies
1
Views
12K
Replies
15
Views
2K
Replies
0
Views
2K
  • Last Post
Replies
1
Views
5K
Replies
3
Views
2K
Replies
1
Views
5K
Top