Question

03 Exercise 7 02 от OI Eight wires cut the page perpendicularly at the points shown in Fig. 15-42. A wire labeled with the integer k (k-1, 2, . . . , 8) carries the current k, ,where i- 4.50 mA. For those wires with odd k, the current is out of the page; for those with even k, it is into the page. Evaluate y B ds. along the closed path indicated and in the direction shown.

Answer 1

given

i_enclosed = 4.5 mA

i_enclosed = 4.5 x 10^-3 A

using equation

$\oint$B.ds = $\mu$_o i_enclosed

from the given figure,

the currents inside of figure are 1 , 3 , 7 and 6

then i_enclosed = 1 + 3 + 7 - 6

= 11 - 6

= 5

so it is

$\oint$B.ds = 5 $\mu$_o i_enclosed

= 5 x 4 x 3.14 x 10^-7 x 4.5 x 10^-3

$\oint$B.ds = 2.826 x 10^-8 T.m