Linear, Second Order Differential Equations -

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Section 4.3 (4, 8, 34)

3

34. RLC Series Circuit. In the study of an electric circuit consisting of a resistor, capacitor, inductor, and an electromotive force (see Figure 4.9), we are led to an initial value problem of the form

where is the inductance in henrys, R is the resistance in ohms, is the capacitance in farads,, is the electromotive force in volts, is the charge in coulombs on the capacitor as time t, and is the current in amperes. Find the current at time if the charge on the capacitor is initially zero, the initial current is zero;

[Hint: Differentiate both sides of the differential equation in (20) to obtain a homogenous linear second-order equation for Then use (20) to determine

Section 4.4 (2, 6, 19)

Section 4.3 (4, 8, 34)

??

.

??

"

-

????

'

+

??????

=

??

??

.

????

"

-

????

'

+

??????

=

??

3

34. RLC Series Circuit

. In the study of an electric circuit consisting of a resistor, capacitor,

inductor, and an electromotive force (see

Figure 4.9)

, we are led to an initial value problem of

the form

??

????

????

+

????

+

??

??

=

??

?

??

?

,

??

?

??

?

=

??

??

,

??

?

??

?

=

??

??

w

here

??

is the inductance in henrys, R is the resistance in ohms,

??

is the

capacitance in

farads,

??

(

??

)

, is the electromotive force in volts,

??

(

??

)

is the charge in coulombs on the capacitor

as

time t, and

??

=

????

????

is the current in amperes. Find the

current

at time

??

if the charge on the

capacitor is initially zer

o, the initial

current is zero;

??

=

10

??

,

??

=

20

?

,

C

=

?

6260

?

-

1

??

,

??????

??

?

??

?

=

100

??

.

[Hint:

Differentiate

both sides of the

differential equation in (20) to obtain a

homogenous

linear

second

-

order equation for

??

?

??

?

.

Then

use (20) to determine

????

??

??

????

??

=

0

Section 4.4 (2, 6, 19)

??

.

??

"

-

????

'

+

????

=

??

??

??????

?

????

??

.

??

"

(

??

)

+

??

??

'

(

??

)

-

??

(

??

)

=

??????

??

????

.

????

"

+

??????

'

-

????

=

-

??

????

-

????

Section 4.3 (4, 8, 34)

??. ??"-????' + ??????=??

??. ????"-????' + ??????=??3

34. RLC Series Circuit. In the study of an electric circuit consisting of a resistor, capacitor,

inductor, and an electromotive force (see Figure 4.9), we are led to an initial value problem of

the form

??

????

????

+????+

??

??

=????,????=??

??

,????=??

??

where ?? is the inductance in henrys, R is the resistance in ohms, ?? is the capacitance in

farads, ??(??), is the electromotive force in volts, ??(??) is the charge in coulombs on the capacitor

as time t, and ??=

????

????

is the current in amperes. Find the current at time ?? if the charge on the

capacitor is initially zero, the initial current is zero;

??=10 ??,??=20 ?,C=6260

-1

??,?????? ????=100 ??. [Hint: Differentiate both sides of the

differential equation in (20) to obtain a homogenous linear second-order equation for ????. Then

use (20) to determine

????

????

???? ??=0

Section 4.4 (2, 6, 19)

??. ??"-????'+????=??

??

??????? ????

??. ??"(??) +????'(??) - ??(??)=?????? ??

????.????"+??????'-????=-??????

-????