PHYS-F-205 - Electricité et magnétisme Correction séance 6

Z~
B·~ dS =Zcos 30BdS = cos 30BS = 1,73mW eb
e
|e|=|∆φ|
∆t=BS −0 0,2=0,4×0,25 0,2= 0,5V
φ(t) = NB(t)S e =
−NS dB(t)
dt e[0,0.3s] [0.3s, 0.4s]
[0.4s, 0.5s]
e=−2,5×0,3
0,3=−2,5V0< t < 0,3s
e= 0 0,3s < t < 0,4s
e=−2,5×(0−0,3
0,5−0,4) = 7,5V0,4s < t < 0,5s

e=Blv cos θ B l
v θ
e= 1,5×10−4×1×2,8×cos 50 = 2,4×10−4V
F~
Fl=I~ l×~ B
I=ξ/R
|ξ|=d
dt BS cos 0 = Bvl Fl=IlB =
Bvl
RlB =(Bl)2v R=Fext
~
Fext ·~v =(Bl)2v
Rvcos 0 = (Blv)2 R
PJoule =RI2=R(Bvl
R)2=(Bvl)2 R
~
Ei
φM
I~
Ei·~ dl =−dφM
dt .

r
θ
φM=BπR2=
CtπR2R C T/s
Z2π
0
Eirdθ =−d
dtCtπR2
2πrEi=−CπR2
⇒Ei=−CR2
2r
w= 2πf = 2π×50 = 314,1rad/s
B
ξ=NSB sin(wt)
B=ξ
NSw = 26,5mT
~
E=~v ×~ B=vB ~v ~ B⊥v=wr
ξ= 2lvB = 2lwrB = 0,3×10 ×2π×0,6 = 1,13 V
V=LdI
dt +RI
dI
dt =V−RI L.

t= 0 ⇒dI/dt =V/L = 120/(50 ×10−3)=2,4×103A/s
t=L/R I = 0,63V/R I 63% ⇒dI/dt =
(V−0,63V)/L = 0,37V/L = 0,8×103A/s
φ
R
e=−dφ/dt
z φ =
Blz e =RI
e=R I =−dφ
dt =−B l dz dt
dz/dt v
I=−Blv/R
~
Fl=BIl ~ 1z=−(Bl)2v
R~
1z
~
dS
I

z
mdv
dt =mg −(Bl)2v R
v= 0 dv/dt =mg
mg −(Bl)2v/R > 0
dv/dt = 0 v=gmR/(Bl)2
i(t)
a
di/dt = 9,60 A/s a = 12,0cm b = 36,0cm
L= 24,0cm
B=µ0i(t)/2πr r
φ=Zb
aZL 0
µ0i(t)
2πr dzdr =Lµ0i(t)ln(r) 2πb
a
=Lµ0i(t)
2πln(b a).
|e|= +dφ
dt =Lµ0 2π
di(t)
dt ln(b a)=0,9×10−7V