problemas capitulo 7 alexander

7/26/2019 Problemas Capitulo 7 Alexander

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(b) If the output is to be an integrated form of theinput, what is the maximum value the pulsewidth can assume?

300 k

+ 200 pFi

(a)

0 T t

Vm

i

(b)

For Prob. 7.75.

7.76 An circuit may be used as a differentiator if theoutput is taken across the inductor and (say

0 1 ), where is the width of the input pulse.If is fixed at 200 k , determine the maximumvalue of required to differentiate a pulse with

10 s.

7.77 An attenuator probe employed with oscilloscopeswas designed to reduce the magnitude of the inputvoltage by a factor of 10. As shown in Fig. 7.141,the oscilloscope has internal resistance andcapacitance , while the probe has an internalresistance . If is fixed at 6 M , find and

for the circuit to have a time constant of 15 s.

oi

Probe Scope

Rp

CsRs

For Prob. 7.77.

7.78 The circuit in Fig. 7.142 is used by a biology studentto study frog kick. She noticed that the frogkicked a little when the switch was closed butkicked violently for 5 s when the switch was

opened. Model the frog as a resistor and calculateits resistance. Assume that it takes 10 mA for thefrog to kick violently.

50

2 H

+

12 V

Switch

Frog

For Prob. 7.78.

7.79 To move a spot of a cathode-ray tube across thescreen requires a linear increase in the voltageacross the deflection plates, as shown in Fig. 7.143.Given that the capacitance of the plates is 4 nF,sketch the current flowing through the plates.

Rise time = 2 ms Drop time = 5 s

t

10

(V)

(not to scale)

For Prob. 7.79.

problemas capitulo 7 alexander

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