1.
ENG17, Sec. 2 (Montgomery)
Spring 2014
due by 11:45am, Tuesday 5/6/14 (in HW box in Kemper 2131)
(P6.4) The triangular current pulse shown below is applied to a 20 mH inductor. a.
Write the expressions that describe i(t) in the four intervals t
< 0, 0 ≤ t
≤ 5 ms,
5 ms ≤ t
≤ 10 ms, and t
> 10 ms. b.
Derive the expressions for the inductor voltage, power, and energy. Use the passive sign convention.
2.
(P6.14) The current shown below is applied to a 0.25 μ F capacitor. The initial voltage on the capacitor is 0 V. a.
Find the charge on the capacitor at t = 15 μ s. b.
Find the voltage on the capacitor at t = 30 μ s. c.
How much energy is stored in the capacitor by this current?
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3.
(P6.21) Assume that the initial energy stored in the inductors below is zero. Find the equivalent inductance with respect to the terminals a,b.
4.
(P6.26) Find the equivalent capacitance with respect to the terminals a,b for the circuit shown below.
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5.
(P7.4) The switch in the circuit below has been closed for a long time before opening at t
= 0. a.
Find i b.
Find i
1
1
(0 -
(0 +
) and i
2
) and i
2
(0 -
(0 +
).
). c.
Find i
1
(t) for t ≥ 0. d.
Find i
2
(t) for t ≥ 0 + . e.
Explain why i
2
(0 ) ≠ i
2
(0 + ).
6.
(P7.24) The switch in the circuit below is closed at t = 0 after being open for a long time. a.
b.
Find i
1 c.
Find i
1
(0 -
(0 +
) and i
2
) and
Explain why i d.
Explain why i
2
1 i
(0
2
-
(0 -
(0 ).
(0 + ).
) = i
) ≠ i
1
2
(0 +
(0 +
) .
). e.
Find i
1
( t
) for t
≥ 0. f.
Find i
2
( t ) for t ≥ 0 + .
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7.
(P7.36) After the switch in the circuit below has been open for a long time, it is closed at t
= 0. Calculate a.
the initial value of i b.
the final value of i c.
the time constant for t
≥ 0 d.
the numerical expression for i(t) when t ≥ 0
8.
(P7.70) In the circuit below, switch A has been open and switch B has been closed for a long time. At t
= 0, switch A closes. Five seconds after switch A closes, switch B opens.
Find i
L
(t)
for t
≥ 0.
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9.
(P7.84) The capacitor in the circuit shown below is charged to 20 V at the time the switch is closed. If the capacitor ruptures when its terminal voltage equals or exceeds 20 kV, how long does it take to rupture the capacitor?
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