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MCQOPTIONS
This section includes 109 Mcqs, each offering curated multiple-choice questions to sharpen your Active Filter Circuits knowledge and support exam preparation. Choose a topic below to get started.
| 51. |
In Figure 17-1(a)(see question 6), the purpose of R1 is to |
| A. | provide a reference voltage. |
| B. | limit current through the diode. |
| C. | limit voltage to the op-amp. |
| D. | provide output voltage sampling. |
| Answer» C. limit voltage to the op-amp. | |
| 52. |
________ regulation can be defined as the percentage change in the output voltage for a given change in the input voltage. |
| A. | Line |
| B. | Load |
| C. | - |
| D. | - |
| Answer» B. Load | |
| 53. |
What regulated output voltage is provided for the following circuit elements: R 1 = 15 k , R 2 = 35 k , and V Z = 11.2 V? |
| A. | 16.50 V |
| B. | 17 V |
| C. | 17.35 V |
| D. | 18.25 V |
| Answer» C. 17.35 V | |
| 54. |
In a series linear regulator, the control element is a(n) ________ in series with the load. |
| A. | inductor |
| B. | capacitor |
| C. | transistor |
| D. | - |
| Answer» D. - | |
| 55. |
For what range of fixed regulated voltages do the series 78xx regulators provide regulation? |
| A. | +5 V to +24 V |
| B. | +5 V to +24 V |
| C. | –5 V to –24 V |
| D. | None of the above |
| Answer» D. None of the above | |
| 56. |
The larger the value of the capacitor, the smaller the peak current drawn through the rectifying diodes. |
| A. | True |
| B. | False |
| C. | - |
| D. | - |
| Answer» C. - | |
| 57. |
In a shunt linear regulator, the control element is a(n) ________ in parallel with the load. |
| A. | inductor |
| B. | capacitor |
| C. | transistor |
| D. | - |
| Answer» D. - | |
| 58. |
Refer to the given figure. If the output voltage tends to decrease due to an increase in load current, the transistor will conduct for ________ time each cycle. |
| A. | a longer |
| B. | a shorter |
| C. | the same |
| D. | - |
| Answer» B. a shorter | |
| 59. |
This circuit is an example of the ac equivalent of an RC filter. |
| A. | True |
| B. | False |
| C. | - |
| D. | - |
| Answer» C. - | |
| 60. |
Refer to the given figure. If the BE junction of Q 1 opens, the output voltage V OUT will |
| A. | increase. |
| B. | decrease. |
| C. | remain the same. |
| D. | - |
| Answer» C. remain the same. | |
| 61. |
Refer to the given figure. The inductor and capacitor are used for |
| A. | amplifying the error signal. |
| B. | controlling the load current. |
| C. | turning on the pulse-width oscillator. |
| D. | filtering the dc pulse output. |
| Answer» E. | |
| 62. |
What type of regulator offers inherent short-circuit protection? |
| A. | shunt regulators |
| B. | series regulators |
| C. | three-terminal regulators |
| D. | switching regulators |
| Answer» B. series regulators | |
| 63. |
The 7905 regulator IC provides ________. |
| A. | 5 V |
| B. | –5 V |
| C. | 12 V |
| D. | –12 V |
| Answer» C. 12 V | |
| 64. |
For what range of load current can voltage regulators be selected for operation? |
| A. | Hundreds of picoamperes to tens of nanoamperes |
| B. | Hundreds of picoamperes to tens of milliamperes |
| C. | Hundreds of milliamperes to tens of amperes |
| D. | None of the above |
| Answer» D. None of the above | |
| 65. |
Switching regulators are more efficient than linear regulators and are particularly useful in ________-voltage, ________-current applications. |
| A. | high, high |
| B. | low, high |
| C. | high, low |
| D. | - |
| Answer» C. high, low | |
| 66. |
Across which of the following components of a power supply does the average (dc) voltage exist? |
| A. | Diodes |
| B. | Secondary of the transformer |
| C. | Capacitor filter |
| D. | None of the above |
| Answer» D. None of the above | |
| 67. |
Voltage regulation requires |
| A. | only line regulation. |
| B. | only load regulation. |
| C. | a constant load. |
| D. | load and line regulation. |
| Answer» E. | |
| 68. |
Which component(s) set(s) the voltage across the load in a basic transistor shunt regulator? |
| A. | Zener diode |
| B. | Transistor base-emitter voltage |
| C. | Both the Zener diode and the transistor base-emitter voltage |
| D. | None of the above |
| Answer» D. None of the above | |
| 69. |
In this op-amp series regulator circuit, which of the following components is the comparator circuit? |
| A. | Op-amp |
| B. | Transistor Q 1 |
| C. | R 1 and R 2 resistors |
| D. | Zener diode |
| Answer» B. Transistor Q 1 | |
| 70. |
What are the typical values of V ref and I adj for the LM317 adjustable voltage regulator? |
| A. | 1.0 V, 100 mA |
| B. | 1.5 V, 100 mA |
| C. | 1.25 V, 100 ?A |
| D. | 1.25 V, 10 mA |
| Answer» D. 1.25 V, 10 mA | |
| 71. |
How many terminals does a 7800 series IC regulator have? |
| A. | 2 |
| B. | 3 |
| C. | 4 |
| D. | none of the above |
| Answer» C. 4 | |
| 72. |
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. |
| A. | 3.2% |
| B. | 3.59% |
| C. | 4.03% |
| D. | 4.59% |
| Answer» B. 3.59% | |
| 73. |
Refer to the given figure. If a solder splash shorted the ends of R 1 to each other, |
| A. | the op-amp would fail. |
| B. | Q 1 would open. |
| C. | the output voltage would not change. |
| D. | the zener would fail. |
| Answer» E. | |
| 74. |
What is the range of the voltage level of the LM317 adjusted voltage regulator? |
| A. | 0 V to 5 V |
| B. | 1.2 V to 37 V |
| C. | –5 V to –24 V |
| D. | 5 V to 24 V |
| Answer» C. –5 V to –24 V | |
| 75. |
________ regulation can be defined as the percentage change in the output voltage for a given change in load current. |
| A. | Line |
| B. | Load |
| C. | - |
| D. | - |
| Answer» C. - | |
| 76. |
How many diodes conduct in the full-wave bridge rectifier while the capacitor is being charged? |
| A. | 1 |
| B. | 2 |
| C. | 3 |
| D. | 4 |
| Answer» C. 3 | |
| 77. |
In an improved shunt regulator, which of the following components sets the reference voltage? |
| A. | Transistor Q 1 |
| B. | Zener diode |
| C. | Transistor Q 2 |
| D. | R S |
| Answer» C. Transistor Q 2 | |
| 78. |
Refer to the given figure. If the load is short-circuited, what would be the maximum current through R 1 ? |
| A. | 1 A |
| B. | 1.2 A |
| C. | 1.5 A |
| D. | 5 A |
| Answer» D. 5 A | |
| 79. |
Calculate the dc voltage across a 2-k load for an RC filter section (R = 50 , C = 20 F). The dc voltage across the initial filter capacitor is V dc = 50 V. |
| A. | 40.78 V |
| B. | 42.78 V |
| C. | 45.78 V |
| D. | 48.78 V |
| Answer» E. | |
| 80. |
In a simple series regulator circuit, which of the following components is the controlling element? |
| A. | Load resistor |
| B. | Zener diode |
| C. | Transistor Q 1 |
| D. | None of the above |
| Answer» D. None of the above | |
| 81. |
Refer to the given figure. The purpose for the zener diode D 1 is |
| A. | to supply a reference voltage. |
| B. | to amplify the error signal. |
| C. | to sense the error signal. |
| D. | to limit the input voltage to the circuit. |
| Answer» B. to amplify the error signal. | |
| 82. |
In a series regulator, what is the purpose of fold-back limiting? |
| A. | to provide more current in the case of a short circuit |
| B. | to limit output voltage if input voltage goes too high |
| C. | to bypass the pass-transistor, if the pass-transistor should fail |
| D. | to provide current up to a maximum, but drop current to a lower value when the output becomes shorted, to prevent overheating of the device |
| Answer» E. | |
| 83. |
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. |
| A. | True |
| B. | False |
| C. | - |
| D. | - |
| Answer» B. False | |
| 84. |
In which of the following applications is a pulsating dc voltage suitable? |
| A. | Battery charger |
| B. | Radio |
| C. | Stereo system |
| D. | Computer |
| Answer» B. Radio | |
| 85. |
Refer to the given figure. If the output of the circuit were to be a short circuit, what power rating would R 1 need to have? |
| A. | 2.25 W |
| B. | 5 W |
| C. | 10 W |
| D. | 22.5 W |
| Answer» E. | |
| 86. |
In this improved series regulator circuit, which of the following components is the sampling circuit? |
| A. | Zener diode |
| B. | Load resistor |
| C. | Either of the two transistors Q 1 or Q 2 |
| D. | Resistors R 1 and R 2 |
| Answer» E. | |
| 87. |
In which period is the capacitor filter charged in a full-wave rectifier? |
| A. | The time during the positive cycle |
| B. | The time during which the diodes are not conducting |
| C. | The time during which the diode(s) is (are) conducting |
| D. | The time during the negative cycle |
| Answer» D. The time during the negative cycle | |
| 88. |
What is the purpose of an additional RC filter section in a power supply circuit? |
| A. | Increase the dc voltage component |
| B. | Increase the ac voltage component |
| C. | Decrease the ac voltage component |
| D. | None of the above |
| Answer» D. None of the above | |
| 89. |
For a full-wave rectifier with ac ripple at 120 Hz, the impedance of a capacitor can be calculated using X C = ________. |
| A. | 0.707 ÷ C |
| B. | 1.414 ÷ C |
| C. | 1.3 ÷ C |
| D. | 0.785 ÷ C |
| Answer» D. 0.785 ÷ C | |
| 90. |
In Figure 17-1(a)(see question 6), the purpose of R 1 is to |
| A. | provide a reference voltage. |
| B. | limit current through the diode. |
| C. | limit voltage to the op-amp. |
| D. | provide output voltage sampling. |
| Answer» C. limit voltage to the op-amp. | |
| 91. |
Refer to the given figure. This circuit is called |
| A. | a series-pass voltage regulator. |
| B. | a shunt voltage regulator. |
| C. | a step-up switching regulator. |
| D. | a step-down switching regulator. |
| Answer» E. | |
| 92. |
A switching regulator that is configured as a voltage-inverter produces what type of output? |
| A. | an ac output with opposite phase to the input ac |
| B. | a dc output that is the negative of the dc input voltage |
| C. | an output that is a higher voltage than the input voltage |
| D. | an ac output from a dc input voltage |
| Answer» C. an output that is a higher voltage than the input voltage | |
| 93. |
A voltage regulator has a no-load output of 18 V and a full-load output of 17.3 V. The percent load regulation is |
| A. | 0.25%. |
| B. | 96.1%. |
| C. | 4.05%. |
| D. | 1.04%. |
| Answer» D. 1.04%. | |
| 94. |
Calculate the ripple of a filter output having a 20-V dc component and a 1.7 V r (rms) ac component. |
| A. | 6% |
| B. | 8.5% |
| C. | 85% |
| D. | 58% |
| Answer» C. 85% | |
| 95. |
What is the ratio of the period of the output voltage to the period of the input voltage in a full-wave rectifier? |
| A. | 0 |
| B. | 0.5 |
| C. | 1 |
| D. | 2 |
| Answer» C. 1 | |
| 96. |
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. |
| A. | 0 |
| B. | 1 |
| C. | 99 |
| D. | 100 |
| Answer» B. 1 | |
| 97. |
What is the typical dropout voltage for the 7812 fixed positive voltage regulator? |
| A. | 4 mV |
| B. | 100 mV |
| C. | 1.5 V |
| D. | 2 V |
| Answer» E. | |
| 98. |
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. |
| A. | 27.9 V |
| B. | 32.12 V |
| C. | 37.78 V |
| D. | 40 V |
| Answer» D. 40 V | |
| 99. |
Switching regulator efficiencies can be greater than ________ percent. |
| A. | 60 |
| B. | 70 |
| C. | 80 |
| D. | 90 |
| Answer» E. | |
| 100. |
The 7912 regulator IC provides ________ . |
| A. | 5 V |
| B. | –5 V |
| C. | 12 V |
| D. | –12 V |
| Answer» E. | |