Formule iz Osnova Elektrotehnike (I dio) koje se mogu...
Transcript of Formule iz Osnova Elektrotehnike (I dio) koje se mogu...
Formule iz Osnova Elektrotehnike (I dio) koje se mogu koristiti na meduispitima
ε0 = 8.854 · 10−12 As
V m
εr =ε
ε0
F =Q1Q2
4πεd2~E =
~F
Q
E =σ
εE =
Q
4πεr2
ϕA =Wp
Q
ϕ(x) = −E · x+ ϕ0
UAB = ϕA − ϕB
A12 = W1 −W2 = QU12
C =Q
UC = ε
S
d
WC =QU
2=Q2
2C=CU2
2
I =Q
t
J = NQv J = κE =I
S
R =U
I=
1G
R = ρl
SG = κ
S
l
Rϑ = R20[1 + α(ϑ− 20
W = I2Rt
P = UI = I2R =U2
R−−−−−−−−−−−−−−−−−Ruk = R1 +R2 + . . .+Rn (ser.)
1Ruk
=1R1
+1R2
+ . . .1Rn
(par.)
1Cuk
=1C1
+1C2
+ . . .1Cn
(ser.)
Cuk = C1 + C2 + . . .+ Cn (par.)
niz∑j=1
Uiz =nR∑k=1
Rk · Ik (petlja)
U = Ik. Ri
ηnaponski =Rt
Rt +Riηstrujni =
Ri
Rt +Ri
R1 ·R3 = R2 ·R4
(mosni spoj)
transformacija: trokut −→ zvijezda
R1 =R12R31
(R12 +R23 +R31)
R2 =R23R12
(R12 +R23 +R31)
R3 =R31R23
(R12 +R23 +R31)
transformacija: zvijezda −→ trokut
R12 = R1 +R2 +R1R2
R3
R23 = R2 +R3 +R2R3
R1
R31 = R3 +R1 +R3R1
R2
µ0 = 4π · 10−7 V s
Am
~F = Q(~v × ~B)
~F = I(~l × ~B) |~F | = IlB sin(α)
B = µ0I
2πr Φ = ~B~S = BS cos(α)
ui = Blv eind = −N dΦdt
= −Ldidt
L = NΦI
M12 = N2Φ12
I1
M = k√L1L2 eM = −M di
dt
uL(t) = Ldi(t)dt
uM (t) = Mdi(t)dt
WL =LI2
2−−−−−−−−−−−−−−−−−
−−−−−−−−−−−−−−−−−
−−−−−−−−−−−−−−−−−
−−−−−−−−−−−−−−−−−
−−−−−−−−−−−−−−−−−
−−−−−−−−−−−−−−−−−
Ief =Im√
2Uef =
Um√2
f =1T
ω = 2πf
a = b+ jc = Aejα = A 6 α
b = Re{a} = A cosα
c = Im = A sinα
A =√b2 + c2
u(t) = Um sin (ωt+ α)
u = Umej(ωt+α)
Um = Umejα U = Uejα = U̇
u(t) = Im{u}
XL = ωL BL =1ωL
XC =1
ωCBC = ωC
Z R ± jX ϕ = arctan( )
Y = G ∓ jB ψ = arctan(B)
ϕ = −ψ
−−−−−−−−−−−−−−−−−
Frekvencijske karakteristike:Im{Z} = 0 Im{Y } = 0
ω0 =1√LC
serija RLC:
Z(ω) =√R2 + (ωL− 1
ωC)2
ϕ(ω) = arctanωL− 1
ωC
R
ρ =
√L
C
paralela RLC:
Y (ω) =√
(1R
)2 + (ωC − 1ωL
)2
ψ(ω) = arctanωC − 1
ωL
γ1
=
paralela RL i RC:
ω0 =1√LC
√√√√R2L −
LC
R2C −
LC
1R
−−−−−−−−−−−−−−−−−
−−−−−−−−−−−−−−−−−
{a}
k =Φ12
Φ1
2
ind
=ρ
R
|~F | = sin(α)Q Bv
1
n∑j=1
Ij = 0 (c̆vor)
n∑j=1
j =0U
∑=
∑I I
izlu
p.h. s.
U=E d·
|~F | =1
µ0I2· I1· l
2π d
QS =QPγ
−−−−−−−−−−−−−−−−−
−−−−−−−−−−−−−−−−−
−−−−−−−−−−−−−−−−−
−−−−−−−−−−−−−−−−−=Umcos(ωt+α) Umsin(ωt+α)+j
=
=GG
G
)]
XR R
=Umsin(ωt+α)
U6 α=