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Unformatted text preview: ESC 120 Test 2 Fall 2008 Answer ALL questions. Questions are approximately equally weighted 130- Independent & dependent
constant sources & resistors The box above contains independent and dependent constant (DC) sources and resistors.
To determine the contents of the box, an engineer attached a variable resistor to the box and measured the current out of the box. When RL was set to 20, the current was 0.5 amps; when RL was set to 120, the current I was 0.25 amps. By assuming a Thevenin
equivalent of the box, or otherwise, 1) Find the resistor value to which RL should be set to maximize the power
dissipated by RL.
ii) Find the maximum power that RL can dissipate.
109 Figure 1b The switch in the circuit in Figure 1b, was at position A for a long time prior to t = 0. At t = 0, the switch moves to position B. Calculate:
dV di V 0+ , i 0+ ,—9 ,—4
9( ) 4( ) dt l=0+ dt l=0+ Figure 2 In Figure 2 above, the op-amp is ideal. The supply voltages for the op-amp are both :15
volts. Calculate and sketch V0(t) if Vin(t) is
a) 3 3
)2e _ t0 Figure 3 12!) Switch A in Figure 3 opens at t = 0 after being closed for a long time prior to t = 0. At t =
2, switch B closes after being open for a long time. Find: a) i(0+) b) i(t)for0<t<2 0) i(2)
d) i(t) for t > 2 ...
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- Spring '08