d⃗
B=µ0
4π
I d⃗
l×⃗r
r3
µ0= 4π×10−7T·m/A
⃗
B
d= 0.1 m I= 10 A
L= 2 m I= 5 A
d= 0.5 m
0.2 m I1=
8 A I2=−8 A
I= 15 A d
2×10−5T
5×10−5T
R= 0.05 m I= 20 A
z= 0.1 m
z≫R
n= 100 I= 2 A
L= 0.5 m n= 200
I= 3 A
R= 0.1 m
I= 10 A d=R
1
/
2
100%
