EXAMPLE 2 An Electrical Network Solve the system in (5) under the conditions E(t) = 60 V, L = 1 h, R = 50 N, C = 10¬4 f, and the currents i¡ and iz are initially zero. %3D SOLUTION We must solve di + 50i, = 60 dt diz 50(10-4) + iz – i = 0 dt subject to i (0) = 0, i2(0) = 0. Applying the Laplace transform to each equation of the system and simplifying gives %3D 60 sl(s) + 501,(s) S -2001 (s) + (s + 200)I¿(s) = 0, where 1,(s) = L{i(t)} and I½(s) decomposing the results into partial fractions gives L{i>(t)}. Solving the system for I and I2 and 60s + 12,000 6/5 6/5 60 1 (s) : s(s + 100)² s + 100 (s + 100)² 12,000 6/5 6/5 120 I(s) s(s + 100)² s + 100 (s + 100)²" S Taking the inverse Laplace transform, we find the currents to be 6. i;(t) 6. -100t е 60te-100t - 5 6. iz(t) 5 -100t е 5 120te-100t - -

Advanced Engineering Mathematics
10th Edition
ISBN:9780470458365
Author:Erwin Kreyszig
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Chapter2: Second-order Linear Odes
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The example 2 on page 297 solves a system of equations for an electrical network. Analyze it and describe the steps taken for the solution (please write it in the computer step by step, like "step 1-...") you only have to write the steps, don't solve it. 

Book: Differential equations with boundary problems (7th edition)

Topic: Laplace Transform

 

EXAMPLE 2
An Electrical Network
Solve the system in (5) under the conditions E(t) = 60 V, L = 1 h, R = 50 N,
C = 10-4 f, and the currents ij and iz are initially zero.
SOLUTION
We must solve
di
+ 50i,
dt
60
50(10-4) diz
+ iz – i = 0
dt
subject to i1(0) = 0, i2(0) = 0.
Applying the Laplace transform to each equation of the system and simplifying
gives
%3|
60
sl,(s) +
501,(s)
S
-2001 (s) + (s + 200)I2(s)
0,
where I,(s)
decomposing the results into partial fractions gives
L{i;(t)} and I,(s)
L{i>(t)}. Solving the system for I1 and I2 and
60s + 12,000
6/5
6/5
60
1(s)
||
s(s + 100)?
s + 100
(s + 100)?
S
12,000
6/5
6/5
120
,(s)
s(s + 100)?
(s + 100)2"
S
s + 100
Taking the inverse Laplace transform, we find the currents to be
i,(t)
6.
-100t
e
60te-100t
|
6
i>(1)
-100t
е
120te
>-100t
5
Transcribed Image Text:EXAMPLE 2 An Electrical Network Solve the system in (5) under the conditions E(t) = 60 V, L = 1 h, R = 50 N, C = 10-4 f, and the currents ij and iz are initially zero. SOLUTION We must solve di + 50i, dt 60 50(10-4) diz + iz – i = 0 dt subject to i1(0) = 0, i2(0) = 0. Applying the Laplace transform to each equation of the system and simplifying gives %3| 60 sl,(s) + 501,(s) S -2001 (s) + (s + 200)I2(s) 0, where I,(s) decomposing the results into partial fractions gives L{i;(t)} and I,(s) L{i>(t)}. Solving the system for I1 and I2 and 60s + 12,000 6/5 6/5 60 1(s) || s(s + 100)? s + 100 (s + 100)? S 12,000 6/5 6/5 120 ,(s) s(s + 100)? (s + 100)2" S s + 100 Taking the inverse Laplace transform, we find the currents to be i,(t) 6. -100t e 60te-100t | 6 i>(1) -100t е 120te >-100t 5
Note that both i(t) and i2(t) in Example 2 tend toward the value
E/R =
as t→0. Furthermore, since the current through the capacitor is
i3(t) = i(t) – i2(t) = 60te¬100r, we observe that i3(t) → 0 as t→ o.
Transcribed Image Text:Note that both i(t) and i2(t) in Example 2 tend toward the value E/R = as t→0. Furthermore, since the current through the capacitor is i3(t) = i(t) – i2(t) = 60te¬100r, we observe that i3(t) → 0 as t→ o.
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