# boylestad electronics multiple choice q&a chapter (15)

August 17, 2017 | Author: Denaiya Watton Leeh | Category: Rectifier, Power Supply, Capacitor, Electrical Equipment, Manufactured Goods

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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.

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

23%

27 Incorre ct:

77%

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

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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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).

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.

18.

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

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?

22.

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

23.

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