EXERCISES DENT1233
(a)
Apply Superposition Theorem to calculate voltage across resistor 120Ω in Figure below.
2A
40 Ω
80 Ω
120 Ω
4V
(b)
By referring Figure below,
(i)
find the Norton equivalent circuit at terminal ab for the modified circuit.
(ii)
find VTH, RTH and its equivalent circuit using Thevenin theorem.
(iii)
determine RL so that maximum power transfer can be achieved at the load resistor. Then, calculate the
value of maximum power transfer.
a
30 Ω
450 V
40 Ω
40 Ω
25 Ω
b
20 Ω
(c)
The switch in Figure has been closed for a long time, at t = 0 it was then opened.
i.
Find v(t) for t > 0.
ii.
How long will it takes for the capacitor voltage to decay to one third of v(0)?
t=0
40 Ω
50 Ω
15 V
(d)
20 mF
The switch in Figure has been in position A for a long time. At t =0, the switch moves to B.
i.
Find initial voltage, v(0), capacitor voltage, v(∞) and time constant, τ.
ii.
Show the complete response, v(t).
iii.
Produce the value v(t) at t =1s and 3s.
A
B
300 Ω
500 Ω
200 Ω
12 V
+
v(t)
-
1 mF
10 V
(e) Referring to Figure, predict the v(t) and i(t). Given input voltage, 𝑉𝑠 = 10cos⁡(4𝑡).
i(t)
2H
50 Ω
30 Ω
Vs
+
v(t)
-
500 mF
(f)
Determine the input impedance, Zin from Figure. Assume that the circuit operates at 𝜔 = 5⁡𝑟𝑎𝑑/𝑠.
1H
Zin →
20 mF
10 Ω
(g) The switch in Figure has been closed for a long time, it was then opened at t = 0.
(i) Find v(t) for t > 0
(ii) Point out the time necessary for the capacitor voltage to decay to one third of v(0).
150Ω
12V
50Ω
40mF
+
v(t)
-