Homework 5

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Exam: 387017RR - Resonant Circuits

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Questions 1 to 20: Select the best answer to each question. Note that a question and its answers may be split across a page break, so be sure that you have seen the entire question and all the answers before choosing an answer.

1. In the circuit shown, if the value of the reactive component was increased, how would it change the waveforms?

A. The phase shift between the current and the voltage would increase.

B. The phase shift between the current and the voltage would reverse.

C. The phase shift between the current and the voltage would decrease.

D. The phase shift between the current and the voltage would remain the same.

2. Look at the phasor diagram and the circuit shown. The diagram shows the impedances for the components in the circuit. What is the total impedance of the circuit?

Voltage

R = 300n (A) (B)

A. 85 a

B. 500 £2

C.100O

D. 50 a

A-

100V

B 100V^

100V D

3. In the circuit above, if you placed meter leads between points A and D, what voltage would you measure?

A.300 V

B. 100 V

C.0V

0. 141 V

4. A parallel-tuned circuit is found to have insufficient bandwidth. You can increase the bandwidth of the circuit by

A. increasing circuit resistance.

B. using the conjugate impedance.

C. adding resistance in parallel.

D. increasing the £"2.

5. Look at this graph of current and voltage phase relationships. The circuit that produces the illustrated current and voltage phase relationships would be

A. inductive with some resistance.

B. purely inductive.

C. purely capacitive.

D. capacitive with some resistance.

B. 1.5.

C. 30.3.

D. 45.5.

Circuits Circuit 4

7. Look at the four circuit diagrams shown. Technician A says that Circuit 3 is a low-pass circuit, and that Circuit 4 is a high-pass circuit. Technician B says that Circuit 1 is a band-pass circuit, and that Circuit 2 is a band-reject circuit. Which of the following statements is correct?

A. Both technicians are correct.

B. Only Technician A is correct.

C. Only Technician B is correct.

D. Neither of the two technicians is correct.

Curve 1 Curve 2

8. Two electronics technicians are looking at the characteristic curves shown. Technician A say that Curve 1 is the curve for a low-pass circuit, and that Curve 2 is the curve for a high-pass circuit. Technician B says that Curve 3 is the curve for a band-pass circuit, and that Curve 4 is the curve for a band-reject circuit. Which of the following statements is correct?

A. Both technicians are correct.

B. Only Technician B is correct.

C. Neither of the two technicians is correct.

D. Only Technician A is correct.

100V

B 100V

c 100V

D—

Voltage

Voltage Voltage

Current

Current Waveform 3 Waveform 4

9. In the circuit shown, the generator Irequency is raised so that it's above resonance. Which of the four labeled waveforms correctly shows the relationship between the voltage and current in the circuit at this time?

A. Waveform 3

B. Waveform 4

C. Waveform 2

D. Waveform 1

10. Two electronics technicians are discussing inductors and capacitors. Technician A says that in a capacitor, energy is stored in the magnetic field. Technician B says that in an inductor, energy is stored in the dielectric material. Which of the following statements is correct?

A. Both technicians are correct.

B. Neither of the two technicians is correct.

C. Only Technician B is correct.

D. Only Technician A is correct.

Voltage Current

Waveform 1

Current Voltage

Waveform 2

Voltage

Waveform 3 Waveform 4

11. The figure shows a circuit diagram and four labeled waveforms. The generator in the circuit is set to operate at the resonant frequency of the components. Which of the four labeled waveforms correctly shows the relationship between the voltage and current in the circuit?

A. Waveform 2

B. Waveform 1

C. Waveform 3

D. Waveform 4

100V

B 100V

c 100V

D 12. In the circuit shown, if you placed meter leads between points A and C, what voltage would you

measure?

A. 200 V

B.0V

C. 100V

D. 141V

13. The LC network at the output of a power supply is an example of a

A. low-pass

B. band-pass

C. band rejection

D. high-pass

filter.

V Receiver

5 H

I 14. Look at the circuit in the figure. This circuit is designed to shunt an interfering signal to ground and prevent it from entering the receiver. What is the frequency of the signal being blocked?

A. 318 kHz

B. 31.8 MHz

C. 31.8 kHz

D. 318 MHz

100V

100V D

15. Look at the circuit above. In measuring the voltages across each of the components in the circuit, you find that they're all equal to 100 V. What is the voltage value of the source?

A. 300 V

B. 141V

C. 100V

D.200 V

16 Look at the characteristic response curve in the figure. The circuit that has this characteristic response curve is designed to couple signals between IF stages in an AM receiver. The circuit that has this characteristic curve would have a bandwidth of

A. 15 kHz.

B. 10 kHz.

C. 455 kHz.

D. 50 kHz.

100V

B-

c ioov

100 V Q-

17. In the circuit in shown above, if you placed meter leads between points B and D, what voltage would

you measure?

A.300 V

B. 100V

C. 141V

D.200 V

300 VAC ©

18. In the circuit shown, suppose that the value of XL is 1000, the value of Xc is lOOfl, and the value of

resistor R1 is lOOfl. What would be the total current and power in the circuit?

A. 1 A at 300 W

B. 3 A at 0 W

C. 3 A at 900 W

D. 3 A at 100 W

19. Two inductors are rated at 150 mH. When you measure the resistance of the two i*ductors> ^you find that one has a measured value of 100 and the other has a measured va ue of 10 &Omega. Wluch inductor would you choose to use in a circuit where the narrowest possible bandwidth is required, and

why? A. Use the 10 £2 inductor because it has a lower Q.

B. Use the 100 H inductor because it has a lower Q.

C. Use the 100 Q inductor because it has a higher Q.

D. Use the 10 Q inductor because it has a higher Q.

300 VAC (JV)

20. Look at the circuit in the figure. The inductive reactance of this circuit is 200 Q the cap^6 reactance of is 100 Q, the capacitive reactance of C2 is 100 a, and the value of resistor R1

What is the total impedance of the circuit?

A.100n

B. 500 n

c.900 a

D. 200 n

End of exam

Exam: 086042RR - Amplifiers

Questions 1 to 25: Select the best answer to each question. Note that a question and its answers may be split across a page break, so be sure that you have seen the entire question and all the answers before choosing an answer.

1. The gain of an amplifier is 0.289 dB. If the input power to the amplifier is 1.5 W, what would be its output power?

A. 7.1795 W

B. 3.1057 W

C. 2.9051 W

D. 1.6032 W

2. A circuit containing two amplifiers connected in series is called a

A. Darlington amplifier circuit.

B. push-pull amplifier circuit.

C. complementary-symmetry amplifier circuit.

D. cascaded amplifier circuit.

3. The output signal of a common-emitter amplifier is

A. 90 degrees out-of-phase with the input signal.

B. in phase with the input signal.

C. 270 degrees out-of-phase with the input signal.

D. 180 degrees out-of-phase with the input signal.

4. An amplifier circuit that's distinguished by its low output impedance and high input impedance is the

A. common-collector amplifier.

B. common-emitter amplifier.

C. common-grid amplifier.

D. common-base amplifier.

5. Amplifiers in Class operation are capable of extremely high gain and a very small amount of distortion.

A. B

B. ab

C. a

D. c

375 MILLIWATTS

1.79 WATTS

6. Look at the amplifier shown. The input power is 375 milliwatts, and the output power is 1.79 watts. What would be the dB gain of this amplifier circuit?

7. The input signal voltage that's needed to forward-bias the base-emitter junction of a silicon transistor is

at least

A. 1.0 V

B.0.8V.

C. 0.6 V.

D. 0.3 V.

8. One point that can be made about Darlington pair circuits is that

A. manufacturers can't produce them easily.

B. they can't be used in small-signal amplifiers for voltage amplification.

C. thermal runaway is considerably more likely than average.

D. they have a high input resistance, and won't load down a pre-stage amplifier.

9. Which of the following amplifier biasing methods is most likely to produce a thermal runaway?

A. The battery-bias method

B. The voltage-divider bias method

C. The basic-bias method

D. The 0 V bias method

10. What is another name for a common-collector circuit?

A. A BiFET amplifier.

B. An emitter-follower circuit

C. A bootstrap circuit

D. A Darlington amplifier

11. The symbol dBm means a dB rating using a reference level of

A. one milliwatt.

B. one microwatt.

C. one megawatt.

A. 1.28 dB

B. 6.78 dB

C. 4.67 dB

D. 8.29 dB

D. one milliampere.

12. The most linear and the most common form of operation used for low power audio amplifiers is Class

A. b.

B. ab.

CC.

D. a.

13. A Class operation is the least efficient.

A. AB

B.B

C. a

d. c

14. In a push-pull amplifier or complementary amplifier, a distortion that can occur near the zero-

amplification line is called

A. intermodulation distortion.

B. frequency distortion.

C. crossover distortion.

D. negative distortion.

15. Frequencies in the range of 20 Hz to 20,000 Hz are said to be in the audio

A. vicinity.

B. display.

C. inclusion.

D. spectrum.

16. The input signal voltage that's needed to forward-bias the base emitter junction of a germanium

transistor is at least

A. 0.3 v.

B. 0.8 v.

C. 1.0 v.

D. 0.6 v.

20 ka

2 V 0—T

8 kQ

1.5 V —O

17. Look at the circuit shown. Using the labeled values in the figure, what would be the dB voltage gain for

the amplifier?

18. For a certain transmission line, the input voltage is 56 uV and the output voltage is 34 uV. Calculate the dB loss in the transmission line.

A. -4.336 dB

B. -1.508 dB

C. -6.259 dB

D. -3.016 dB

19. Which of the following conditions can cause clipping of an amplifier output signal?

A. The amplifier's poor high-frequency amplification

B. An insufficient input signal amplitude

C. The amplifier's poor low-frequency amplification

D. An excessive input signal amplitude

20. A serious problem with Class B operation occurs as the signal crosses the zero-voltage axis. This problem, related to the barrier potential of the base-emitter junction, is called

A. negative feedback.

B. crossover distortion.

C. reverse-biasing.

D. intermodulation distortion.

21. Which of the following classes of amplifier operation is used in almost all high-quality audio power

amplifiers?

A. Class AB

B. Class B

C. Class C

D. Class A

A. 3.62 dB

B. 1.47 dB

C. 7.24 dB

D. 5.91 dB

22. What is the dB gain of an amplifier that has an input power of 136 mW and an output power of 1.08

W? A. 1.36 dB

B. 21 dB

C. 0.245 dB

D. 8.99 d B

23. Which of the following is something called a beta-squared amplifier?

A. A push-pull amplifier

B. A complementary amplifier

C. And emitter-follower amplifier

D. A Darlington amplifier

12 V 11 CI 0.6 V INPUT TRANSMISSION LINE OUTPUT

24. The figure shows a transmission line with an input voltage of 12 V. At the output, the voltage is 10.6 V. What is the dB gain in this transmission line?

A. -0.942 dB

B. -3.926 dB

C.-1.076 dB

D. -5.012 dB

25. The only type of waveform that doesn't contain harmonic frequencies is the

A. square wave.

B. sine wave.

C. triangular wave.

D. sawtooth wave.

End of exam

Exam: 086043RR - Oscillators

1. Which of the following oscillator circuits generates a sawtooth waveform?

A. An Armstrong oscillator circuit

B. A UJT oscillator circuit

C. A Colpitis oscillator circuit

D. A Hartley oscillator circuit

2. In an oscillator circuit, which of the following generates the oscillations and determines the signal's

frequency?

A. The power supply

B. The resonant circuit

C. The feedback system

D. The amplifier

3. The oscillator that's used in a phase-locked loop circuit is a(n)

A. voltage-controlled oscillator.

B. Colpitis oscillator.

C. Hartley oscillator.

D. Armstrong oscillator.

4. In an oscillator circuit, which of the following increases the input signal and delivers the exact amount of power to the resonant circuit needed to sustain continuous oscillation?

A. The power supply

B. The resonant circuit

C. The amplifier

D. The feedback system

5. In an oscillator circuit, which of the following takes a part of the output signal from the amplifier and returns it to the input of the resonant circuit?

A. The amplifier

B. The feedback system

C. The power supply

D. The transistor

6. The coupling capacitor in an Armstrong oscillator

A. is part of the circuit that biases the base of the transistor.

B. shifts the phase of the input signal.

C. determines the resonant frequency of the oscillator.

D. delivers the signal from the LC circuit to the amplifier.

7. Which of the following oscillator circuits uses a tapped inductor?

A. Hartley

B. Colpitts

C. Wien bridge

D. Armstrong

8. The action of the circulating energy in a resonant circuit constantly reverses direction, creating a voltage in the form of a sine wave. This circulating energy effect is called the

A. feedback effect.

B. resonant effect.

C. sawtooth wave effect

D. flywheel effect.

9. Which of the following oscillator circuits uses a tapped capacitor?

A. A Hartley oscillator

B. A Colpitts oscillator

C. A Wien bridge oscillator circuit

D. A UJT oscillator circuit

10. Circulating current in a tuned LC circuit will gradually die out due to losses in the circuit, and the oscillation will eventually stop unless the power is replaced. This occurrence is called the

A. regenerative effect.

B. sawtooth effect.

C. constant-amplitude effect.

D. damping effect.

11. In a unijunction transistor oscillator circuit, the value of R is 2 MQ and the value of C is 0.1 pF. What would be the capacitor-charge time constant of the oscillator?

A. 1 second

B. 0.2 second

C. 20 seconds

D. 0.001 second

12. In the frequency synthesizer, two oscillators deliver their signals to a

A. detector.

B. TCTB oscillator.

C. mixer.

D. regenerative amplifier.

13. Which of the following is a component that opposes any change in voltage across its terminals?

A. A transformer

B. An inductor

C. A capacitor

D. A resistor

14. How is the proper phase shift produced in a phase-shift oscillator?

A. Through an inductor

B. Through a transistor

C. Through RL combinations

D. Through RC combinations

15. The UJT oscillator is also sometimes called a

A. Colpitts oscillator.

B. relaxation oscillator.

C. Wien bridge oscillator.

D. twin-T oscillator.

16. The type of waveform that's generated by a Wien bridge oscillator is a

A. sawtooth wave.

B. sine wave.

C. pulse wave.

D. triangular wave.

17. Which of the following oscillator circuits contains an RC network that's essentially an AC voltage

divider? A. The twin-T oscillator circuit

B. The Wien bridge oscillator circuit

C. The TCTB oscillator circuit

D. The UJT oscillator circuit

18. Which of the following will decrease the resonant frequency of a series-tuned circuit?

A. Increasing the capacitance of the coupling capacitor

B. Increasing the inductance of L

C. Decreasing the capacitance of the coupling capacitor

D. Decreasing the inductance of L

19. Feedback in an Armstrong oscillator is provided by a(n)

A. electromagnetic coupling.

B. coupling capacitor.

C. electrostatic coupling.

D. capacitive coupling.

20. Amplitude control in a practical Wien bridge oscillator can be provided by a/an

A. diode.

B. inductor.

C. capacitor.

D. thermistor.

21. Which of the following oscillators uses a split capacitor?

A. UJT

B. Colpitts

C. TCTP

D. Armstrong

22. By controlling the amount of feedback, an Armstrong oscillator circuit can be converted to a

A. high-gain amplifier.

B. filter.

C. decoupling network.

D. Colpitts oscillator.

23. The normal operating region of the UJT oscillator is the

A. pinch-off region.

B. negative/resistance region.

C. ohmic region.

D. saturation region.

24. A Wien bridge oscillator circuit is a type of

A. LR oscillator.

B. RC oscillator.

C. LCR oscillator.

D. LC oscillator

25. Suppose that you have a 20 jj,F capacitor, and you want to make a series-tuned circuit that has a resonant frequency of 500 Hz. What value of inductance would you need in the circuit?

A. 14 mH

B. 5 mH

C. 10 mH

D. 22 mH

End of exam

Exam: 086024RR - Optoelectronic and Fiber-Optic Components

1. Which type of modulation is most affectedby transient voltages?

A. Pulse amplitude modulation (PAM)

B. Pulse width modulation (PWM)

C. Pulse position modulation (PPM)

D. Pulse code modulation (PCM)

2. Which of the following is a method of obtaining electron emission from a conductor?

A. Electromagnetic emission

B. Piezoelectric emission

C. Photoemission

D. Primary emission

3. Remote controls for modem television receivers use

A. ultraviolet light.

B. infrared light.

C. UHF electromagnetic waves.

D. laser light.

4. Which of the following is correct regarding the length of one angstrom (A)?

A. It's equal to one millionth of a meter

B. It's equal to one tenth of a centimeter

C. It's equal to 1 * 10 "10 meter

D. It's equal to one tenth of an inch

5. Which of the following uses avalanching to provide a higher output current?

A. Phanatron

B. Encoder

C. Photomultiplier

D. Darlington amplifier

6. Which of the following is most likely to use a photovoltaic cell?

A. Hand-held television remote control

B. Remote floodlight

C. Photographer's light exposure meter

D. Bar code reader

7. To reduce heat concentration engineers designed integrated circuits to operate with only

power supply.

A. 5 V

B. ±15 V

C. 1.5 V

D. 2.5 V

8. The wavelength of light is usually measured in

A. angstroms.

B. square centimeters.

C. light days.

D. parsecs.

9. The small dot that's often placed on top of the six-pin optoisolator package indicates

A. the location of pin #1.

B. the location of the signal output pin.

C. that it's an optoisolator.

D. the location of pin #6.

10. The total range of light frequencies (or wavelengths) is called the light

A. spectrum.

B. span.

C. relationship.

D. index.

11. The number of components per square area on an integrated circuit is called the

A. pile up.

B. specific gravity.

C. density.

D. poundage.

12. Increasing the range of frequencies used will communication.

A. increase the number of signals that can be used for

B. automatically reduce the fidelity of

C. decrease the number of signals that can be used for

D. not change the number of signals that can be used for

13. Which of the following is sometimes used as a measure for light waves?

A. Micrometers

B. Millimeters

C. Microinches

D. Milliyards

14. Which of the following can be triggered into conduction by a momentary light pulse?

A. SCR

B. LASCR

C. Four-layer diode

D. Darlington transistor

15. Which of the following light waves has the shortest wavelength?

A. Yellow

B. Blue

C. Green

D. Red

16. The human eye is most sensitive to

A. blue-yellow.

B. blue-green.

C. yellow-green.

D. red-orange.

17. Which of the following can be used as the most sensitive heat detector?

A. PIN diode

B. Bolometer

C. Fuse

D. Vacuum tube

18. Which of the following light waves has the highest frequency?

A. Green

B. Red

C. Yellow

D. Blue

19. A lead is sometimes connected to the base of a phototransistor

A. to establish the maximum frequency of operation.

B. to control sensitivity.

C. because it's a regular transistor that has been converted to a phototransistor.

D. to control bandwidth.

20. The binary number system is made up of

A. the symbols + and

B. Arabic numbers 0 and 1.

C. the letters A and B.

D. roman numerals I and II.

End of exam

Exam: 387018RR - Advanced Electronic Components

1. Two electronics technicians are comparing a full-wave bridge rectifier to a full-wave rectifier that uses two diodes and a center-tapped secondary. Technician A says that the two-diode rectifier has a lower ripple frequency and can supply greater current than the full-wave bridge rectifier. Technician B says that the full- wave bridge rectifier results in full secondary voltage at the output. Which of the following statements is correct?

A. Only Technician A is correct.

B. Neither of the two technicians is correct.

C. Only Technician B is correct.

D. Both of the technicians are correct.

fYYYYYY^ waveform 1

rrrwrw WAVEFORM 3

2. Look at the circuit diagram and the four waveforms that are shown in the figure above. Assume that diode D1 in the circuit is opened. Which of the four waveforms shown in the figure would appear across

rl?

A. Waveform 4

B. Waveform 1

C. Waveform 2

D. Waveform 3

3. A full-wave power supply with a capacitor-input filter is connected to a 400 Hz AC source. The frequency of the ripple waveform at the input to the filter is

A. 800 Hz.

B. 400 Hz.

C. 0 Hz (DC).

D. 100 Hz.

4. Look at the circuit diagram shown in the figure above. When R1 and are equally illuminated, the

lamp ^ glows dimly. Which of the following will happen if ^ is covered so that no light can reach it?

A. Lamp Ij glows brighter, because the forward bias on Qj is decreased.

B. Lamp Ij goes out, because the forward bias on Q1 increases.

C. Lamp Jl goes out, because the forward bias on Qj is decreased.

D. Lamp glows brighter, because the voltage on the base of Qj goes positive.

0 WAVEFORM 1 WAVEFORM 2

WAVEFORMS WAVEFORM 4 5. Look at the circuit diagram and the four waveforms that are shown in the figure above. Assume that the circuit's switch is closed momentarily, then opened. Which of the four waveforms shown will appear between terminals A and B after the switch is opened?

A. Waveform 3

B. Waveform 2

C. Waveform 4

D. Waveform 1

6. The output voltage of a power supply is measured at 12 V with no load connected. The manufacturers specifications say the power supply has a regulation of 10 percent. What is the full-load output voltage of

the power supply?

A. 10.9 V

B. 1.2 V

C. 13.2 V

D. 10.8 V

7. Negative clipping of an output signal occurs when the

A. input impedance is too high.

B. input amplitude is too high.

C. power supply voltage is too high.

D. output impedance is too high.

30 V A

^ 2 kQ 5 V

=<> i OA

8. Look at the circuit diagram that's shown in the figure above. What is the voltage between point A and

ground?

A. -25 V

B. —6 V

C. +6 V

D. +25 V

9. Two electronics technicians are discussing LC and RC oscillators. Technician A says that an RC oscillator doesn't require a resonant circuit. Technician B says that an LC oscillator can be tuned only by varying the inductance, and that an RC oscillator can't produce a sine wave. Which of the following statements is correct?

A. Both of the technicians are correct.

B. Only Technician B is correct.

C. Neither of the two technicians is correct.

D. Only Technician A is correct.

Input output

Circuit A

Circuit B Circuit D 10. Look at the figure above. Which of the following circuits is a properly biased common-emitter circuit?

A. Circuit B

B. Circuit C

C. Circuit A

D. Circuit D

A Q

11. In the circuit shown in the figure above, what is the power level at point A?

A. 0.31 mW

B. 31 mW

C. 310 mW

D. 3.1 mW

30 V

12. In the circuit shown in the figure above, what is the current through

A. 60 mA

B. 6.0 mA

C. 2.5 mA

D. 25 mA

13. A 100 kHz oscillator that's followed by a doubler and two triplers will produce an output frequency of

A. 500 kHz.

B. 800 kHz.

C. 1.8 MHz.

D. 180 kHz.

14. What would happen at the output of a full-wave bridge rectifier circuit if one of the diodes m the bridge

opened? A. The ripple frequency would decrease, and the voltage would decrease.

B. The ripple frequency would increase, and the voltage would decrease.

C. The ripple frequency would remain the same, and the voltage would decrease.

D. The ripple frequency would remain the same, and the voltage would increase.

15. Look at the amplifier circuit shown above. Which of the following statements about this circuit is

correct? A. This is a common-collector circuit that's characterized by a high input impedance and a low output impedance.

B. This is a common-emitter circuit that's characterized by a low input impedance and a high output impedance.

C. This is a common-emitter circuit that's characterized by a high input impedance and a low output impedance.

D. This is a common-collector circuit that's characterized by a low input impedance and a high output impedance.

CIRCUIT 2 CIRCUIT 4 16. Look at the four circuit diagrams that are shown above. Which of these four diagrams represents correctly configured full-wave bridge rectifier circuit?

A. Circuit 1

B. Circuit 3

C. Circuit 4

D. Circuit 2

A Q

5 mW C B

17. Look at the circuit diagram shown in the figure above. What is the power level at point B in the circuit?

A. 0.31 mW

B. 3.1 mW

C. 620 mW

D. 62 mW

18. Which of the following is essential for the operation of an oscillator?

A. An LC circuit

B. Positive feedback

C. Degenerative feedback

D. A unity gain amplifier

19. One advantage of using photon coupling for signal transmission is the

A. lower cost of signal-handling components.

B. greater adaptability to digital transmission.

C. greater immunity to noise pickup.

D. lower power required for transmission.

20. A modulation technique that's used in fiber-optic transmission in which the width of pulses is varied in accordance with the modulation signal is called

A. PWM.

B. PPM.

C. PAM.

D.PRM.

End of exam