boylestad electronics multiple choice q&a chapter (15)

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Your Results for: "Multiple Choice" Site Title: Electronic Devices and Circuit Theory Book Author: Boylestad Location on Site: Chapter 15 > Multiple Choice Date/Time October 12, 2012 at 12:51 AM (UTC/GMT) Submitted:

1.

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Summary of Results 23% Correct of 35 Score d ite m s: 8 C orre ct:

23%

27 Incorre ct:

77%

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In which of the following applications is a pulsating dc voltage suitable? Your Answer: Battery charger

2.

Calculate the ripple of a filter output having a 20-V dc component and a 1.7 Vr(rms) ac component. Your Answer: 6% Correct Answer: 8.5%

3.

Calculate the voltage regulation of a power supply having VNL = 50 V and VFL = 48 V. Your Answer: 4.17%

4.

Across which of the following components of a power supply does the average (dc) voltage exist? Your Answer: Diodes Correct Answer: Capacitor filter

5.

Calculate the ripple voltage of a full-wave rectifier with a 75load drawing 40 mA.

F filter capacitor connected to a

Your Answer: 1.20 V Correct Answer: 1.28 V

6.

What is the ratio of the period of the output voltage to the period of the input voltage in a full-wave rectifier? Your Answer: 0 Correct Answer: 0.5

7.

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A _____ -wave rectified signal has less ripple than a _____ -wave rectified signal and is thus better to apply to a filter.

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Your Answer: full, half

8.

If the value of full-load voltage is the same as the no-load voltage, the voltage regulation calculated is _____ %, which is the best expected. Your Answer: 0

9.

In which period is the capacitor filter charged in a full-wave rectifier? Your Answer: The time during the positive cycle Correct Answer: The time during which the diode(s) is (are) conducting

10.

In which period is the capacitor filter discharged through the load in a full-wave rectifier? Your Answer: The time during the positive cycle Correct Answer: The time during which the diodes are not conducting

11.

If a peak rectified voltage for the full-wave filter circuit is 40 V, calculate the filter dc voltage if C = 75 F and load current is 40 mA. Your Answer: 27.9 V Correct Answer: 37.78 V

12.

Calculate the ripple of a capacitor filter for a peak rectified voltage of 40 V, a capacitor value C = 75 F, and a load current of 40 mA. Your Answer: 3.2%

13.

What is the ratio of the peak ripple voltage level to its rms voltage level? Your Answer:

14.

The larger the value of the capacitor, the smaller the peak current drawn through the rectifying diodes. Your Answer: True Correct Answer: False

15.

What is the purpose of an additional RC filter section in a power supply circuit? Your Answer: Increase the dc voltage component Correct Answer: Decrease the ac voltage component

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16.

Calculate the dc voltage across a 2-k load for an RC filter section (R = 50 The dc voltage across the initial filter capacitor is Vdc = 50 V.

, C = 20

F).

Your Answer: 40.78 V Correct Answer: 48.78 V

17.

The purpose of the added RC section is to pass most of the dc component while reducing as much of the ac component as possible.

Your Answer: True

18.

This circuit is an example of the ac equivalent of an RC filter.

Your Answer: True Correct Answer: False

19.

For a full-wave rectifier with ac ripple at 120 Hz, the impedance of a capacitor can be calculated using XC = _____. Your Answer: 1.414 ÷ C Correct Answer: 1.3 ÷ C

20.

In a simple series regulator circuit, which of the following components is the controlling element? Your Answer: Zener diode Correct Answer: Transistor Q 1

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21.

In this improved series regulator circuit, which of the following components is the sampling circuit?

Your Answer: Load resistor Correct Answer: Resistors R1 and R2

22.

In this op-amp series regulator circuit, which of the following components is the comparator circuit?

Your Answer: Transistor Q 1 Correct Answer: Op-amp

23.

What regulated output voltage is provided for the following circuit elements: R1 = 15 k , R2 = 35 k , and VZ = 11.2 V?

Your Answer: 17.35 V Correct Answer: 17 V

24.

Which component(s) set(s) the voltage across the load in a basic transistor shunt regulator? Your Answer: None of the above Correct Answer: Both the Zener diode and the transistor base-emitter voltage

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25.

In an improved shunt regulator, which of the following components sets the reference voltage? Your Answer: Transistor Q 2 Correct Answer: Zener diode

26.

For what range of load current can voltage regulators be selected for operation? Your Answer: Hundreds of picoamperes to tens of milliamperes Correct Answer: Hundreds of milliamperes to tens of amperes

27.

For what range of fixed regulated voltages do the series 78xx regulators provide regulation? Your Answer: None of the above Correct Answer: +5 V to +24 V

28.

What is the typical dropout voltage for the 7812 fixed positive voltage regulator? Your Answer: 100 mV Correct Answer: 2 V

29.

How many diodes conduct in the full-wave bridge rectifier while the capacitor is being charged? Your Answer: 4 Correct Answer: 2

30.

What is the range of the voltage level of the LM317 adjusted voltage regulator? Your Answer: 5 V to 24 V Correct Answer: 1.2 V to 37 V

31.

What are the typical values of Vre f and Iadj for the LM317 adjustable voltage regulator? Your Answer: 1.25 V, 10 mA Correct Answer: 1.25 V, 100 μA

32.

The 7812 regulator IC provides _____. Your Answer: –12 V Correct Answer: 12 V

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33.

The 7912 regulator IC provides _____ . Your Answer: 5 V Correct Answer: –12 V

34.

The 7905 regulator IC provides _____. Your Answer: 5 V Correct Answer: –5 V

35.

The 7805 regulator IC provides _____. Your Answer: 5 V

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