(. 3), () :
U (t) = U0sin ωt (1.11)
:
I (t) = U (t)/R = U0sin ωt/R = I0 sin ωt (1.12)
, . 4:
I U
. 4
, . :
p (t) = i(t)u(t) = I0 U0 sin ωt = I0 U0(1- cos2 ωt)/2 (1.13)
, (. 5):
, .
:
T T T
P = 1/T ∫ p(t)dt = I0U0/2T ∫ dt − I0U0/2T ∫ cos2ωt dt = (I0U0/2T) ∙T = IU = I R
0 0 0 (1.14)
.
, . , ( ), . .
(. 6), L, (R=0), (1.11):
eL. :
U + eL = 0 (1.15)
, :
eL = −LdI/dt (1.16)
(1.16) (1.15), :
dI/dt = − eL/L = U/L = U0 sin ωt/L (1.17)
, :
I =− U0cos ωt/ω L + const = U0sin (ωt − π/2)/ ωL+ const (1.18)
const , , . . . :
I = I0 sin (ωt − π/2) (1.19)
I0 = U0/ ωL. √2, :
I = U/ ωL= U/ XL (1.20)
(1.20) , XL= ωL .
(1.19) , π/2. 7.
, .
:
p (t)= I0 U0 sin ωt(ωt − π/2)= − I0 U0 sin2 ωt/2 (1.21)
, (. 8).
, .
:
T
P = 1/T ∫ p(t)dt = (− I0 U0 /2T) ∫ sin2 ωt dt = 0 (1.22)
, .