Électromagnétisme III

O R
σ > 0ω
Oz
P(r)I
dr
M Oz
−→
B z = 0
−→
js=σωrˆeθI=σωR2/2
−→
B=µ0σωz
2z
√z2+R2+√z2+R2
z−2ˆez
O R
Ox
I−→ B(O)
O
Ox
q
y
P
I
−→
B(O)
−→
B(O)
µ0I R −→ B(O)
θ
−→
B(O) = B(O) ˆez
−→
B(O) = µ0I
4Rˆez
N
R1R2
M Oz I
R1R2θ1θ2
R1R2M
Rdθ/ cos θ= ln |θ/2 + π/4|
•−→ B(M) = µ0NI
2(R2−R1)ln |θ2/2+π/4| |θ1/2+π/4|+ sin θ1−sin θ2ˆez
N
a ρ
S α
r1r2> r1
z
S r
z
S
a
r1
r2
a
z
N
r1r2a α
dN
z z +dz
dN
dN
R ρ s
l R =ρl/s
R
I
µ0
−→
B S
N= (r2−r1)/(asin α)
dN =dr/ (asin α)
R= 4ρr2
2−r2 1/a3sin α
−→
B(S) = µ0Isin2α
2aln r2 r1ˆez
∼

Oz R
e e R
R−e/2
R+e/2
Oz
B(r)r > R r < R
I
js
B(r)js
−→
B
µ0js
B(r) = µ0I/ (2πr)r > R
∆−→ B1→2=µ0
−→
js∧ˆer,1→2
Ox n
I
n
I−→ j
R1R2
R1R2
j
Axe Ox
r
Ox B0
B B0
r < R1
R1< r < R2r > R2
B0
j I
B0
n I
B(r) = B0−µ0j(r−R1)R1< r < R2
B(r) = B0−µ0j(R2−R1)r > R2
B0=µ0j(R2−R1)
R1
I
R2R3> R2> R1
I
ˆez
M r
−→
B
M
−→
B=
B(r) ˆeθB(r)r
C
B(r)M
µ0I r R1R2R3
•r > R3•R3> r > R2•R2> r > R1
•R1> r −→ B
B(r)
B(r) = µ0I
2πr
R2
3−r2
R2
3−R2 2
R2< r < R3
B(r) = µ0I
2π
r
R2
1
R1> r
O1z
R1−→
j=jˆez
O2z R2
•−→ B=µ0j
2ˆez∧−−−→
O1O2
∼