高等电子测量试题

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山东科技大学2007—2008 学年第一学期

《电子测量技术》考试试卷（A卷）

班级 姓名 学号 SECTION A (Total marks 25)

(Marking scheme: +1 mark for correct answer; -1 for incorrect; 0 for no answer)

Enter T (true) or F (false) against each of the following statements

1. When pressure is measured it is called an indirect measurement. [ ] 2. Telemetry involves sending measurement information between places. [ ] 3. A wattmeter is a direct analogue recording instrument. [ ]

4. An electronic thermometer with an LCD output is a direct digital recording instrument. [ ]

5. When a strain gauge is pulled (stretched) its resistance decreases. [ ] 6. A photo-diode can behave as an electric generator. [ ] 7. A photo-transistor does not have a Base connection. [ ]

8. A thermocouple comprises wires of two different metals joined together. [ ] 9. The piezo effect in a crystal means that changes of pressure will produce changes of voltage. [ ]

10. In an operational amplifier (op-amp) the gain is assumed to be very large. [ ] 11. The op-amp inverting circuit has a negative gain. [ ] 12. The op-amp differentiator circuit requires a switch. [ ]

13. When the op-amp is used as a comparator there is no feedback resistor. [ ] 14. The D’Arsonval movement has a fixed magnet and moving coil. [ ]

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15. The Ayrton shunt is used in multi-range ammeters. [ ] 16. An ohmmeter scale is not linear. [ ]

17. The dynamometer wattmeter has two coils. [ ]

18. The anodes in an oscilloscope are more negative than the cathode. [ ] 19. In an oscilloscope the electrons travel from the screen to the cathode. [ ] 20. The Lissajous figure for two identical sinewaves is a straight line. [ ]

21. In a common-anode 7-segment display the negative voltage is applied to the anode. [ ]

22. The resolution of a voltmeter is the minimum input voltage change that can be detected. [ ]

23. Chart recorders distort the X and Y axes. [ ]

24. ASCII = Australian Science Code for Imitating Insects. [ ]

25. Hysteresis means the upward and downward movements of a meter do not give the same results. [ ]

SECTION B (Total 10 marks)

(Marking scheme: +2 marks for correct answer; -1 for incorrect; 0 for no answer)

山科大 高等电子测量 外语版

Identify the labeled components on the diagram of the D’Arsonval movement above by ticking A, B, C or D. 1. Component V:

A [ ] Permanent magnet B [ ] Moving coilC [ ] Pointer D [ ] Scale 2. Component W:

A [ ] Base plate B [ ] Moving coil C [ ] Magnet D [ ] Scale 3. Component X:

A [ ] Scale B [ ] Pointer C [ ] Magnet D [ ] Helical spring 4. Component Y:

A [ ] Permanent magnet B [ ] Pointer C [ ] Scale D [ ] Screen 5. Component Z:

A [ ] Moving coil B [ ] Helical spring C [ ] Scale D [ ] Pointer

SECTION C (Total 65 marks)

1. (8 marks) For a meter movement of Sensitivity 3500 ohms/volt, what would be

the total resistance of a voltmeter to measure up to 50 volts?

2. (9 marks) An op-amp circuit has four inputs V1, V2, V3, V4 . Design the

circuit to produce an output given by: Vo = -(V1 + 2V2 + 3V3 +4V4) Show the values of the resistors used.

3. (10 marks)

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A photo-diode has the characteristics shown above. It is connected in series with a 200 ohm resistor across a 0.5 volt supply, which provides reverse bias. What will be the voltages across the diode when the light intensities are 1500, 10000, 20000 lm/m2.

4. (8 marks) A resistive strain gauge with a sensitivity factor of 2.5 and initial resistance of 300 ohms is fixed to a steel beam. The mechanical strain of the beam is 2.0%. What would be the change of resistance?

5. (20 marks

)

For the A-D converter shown above, do the following:

(a) Draw the waveforms (on the axes printed below) for Vramp and the voltages at G and X, showing the time values clearly.

(b) Calculate the binary number produced on pins Q0 to Q9 (ten bits).

(c) Calculate the maximum input voltage for which the converter will operate correctly.

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6. (10 marks) Describe six of the main types of measurement error found when

using analogue and digital voltmeters. In each case suggest a way of reducing this type of error.

END OF EXAMINATION PAPER

山科大 高等电子测量 外语版

山东科技大学2008—2009 学年第一学期

《高等电子测量技术》考试试卷（A卷）

班级 姓名 学号

SECTION A (Total marks 25)

Enter T (true) or F (false) against each of the following statements

26. When strain is measured, it is called an indirect measurement. [ ] 27. A data acquisition card contains a fast ADC. [ ]

28. A wattmeter is a direct analogue recording instrument. [ ]

29. In sweep frequency measurements the X-input to the oscilloscope is a varying

frequency. [ ]

30. When a strain gauge is pulled (stretched) its resistance decreases. [ ] 31. A photo-diode can behave as an electric generator. [ ]

32. A GPIB bus can connect different types of measurement equipment together. [ ] 33. A thermocouple comprises wires of two different metals joined together. [ ] 34. A ratio of 100 is equivalent to 3 dB. [ ]

35. Linear regression involves finding the best-fit line. [ ] 36. The op-amp inverting circuit has a positive gain. [ ] 37. The CAN bus was originally designed for use in cars. [ ]

38. When the op-amp is used as a comparator there is no feedback resistor. [ ] 39. ASCII values use nine binary bits. [ ]

40. The Ayrton shunt is used in multi-range ammeters. [ ]

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41. An ohmmeter scale is not linear. [ ] 42. 20 dBm is equivalent to 0.1 Watts. [ ]

43. The anodes in an oscilloscope are more negative than the cathode. [ ] 44. In an oscilloscope the electrons travel from the screen to the cathode. [ ] 45. The Lissajous figure for two identical sinewaves is a straight line. [ ]

46. In a common-anode 7-segment display the negative voltage is applied to the

anode. [ ]

47. The resolution of a voltmeter is the minimum input voltage change that can be

detected. [ ]

48. Random errors can be eliminated by calculating the mean value. [ ] 49. A storage oscilloscope contains flood guns. [ ]

50. When an op-amp is used as a comparator, it is operating in the saturation

region. [ ]

SECTION B (Total 9 marks)

Viewing direction

J

H

B

G

F

E

D

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Identify the labeled components on the diagram above which shows the basic structure of an LCD cell. Put an X in A, B, C or D on the following list: 6. Component A:

A [ ] Liquid crystal B [ ] Conductor matrix C [ ] Glass D [ ] Polariser 7. Component B:

A [ ] Liquid crystal B [ ] Mirror C [ ] Connection bus D [ ] Polariser 8. Component C:

A [ ] Conductor matrix B [ ] Glass C [ ] Mirror D [ ] Polariser 9. Component D:

A [ ] Connection bus B [ ] Glass C [ ] Polariser D [ ] Conductor matrix 10. Component E:

A [ ] Conductor matrix B [ ] Polariser C [ ] Glass D [ ] Mirror 6. Component F:

A [ ] Polariser B [ ] Liquid crystal C [ ] Glass D [ ] Conductor matrix 7. Component G:

A [ ] Mirror B [ ] Polariser C [ ] Connection bus D [ ] Glass 8. Component H:

A [ ] Polariser B [ ] Mirror C [ ] Glass D [ ] Connection bus 9. Component J:

A [ ] Mirror B [ ] Glass C [ ] Polariser D [ ] Liquid crystal

SECTION C (Total 66 marks)

1. (10 marks)

Measurements were made on the circuit shown below over a period of time, and the output voltage values are shown in the table. Plot these values on the graph given below. Draw the best-fit line, and calculate the value of the capacitor C.

-6 V

山科大 高等电子测量 外语版

6

5

4

Vo

3

2

1

024681012141618

time

Graph for Question 1

2. (8 marks).

A stepper motor has four coils and a toothed rotor with 33 teeth. What is the step-angle of this motor?

3. (7 marks)

A resistive strain gauge with a sensitivity factor of 2.5 and initial resistance of 250 ohms is fixed to a steel beam. The mechanical strain of the beam is 2.0%. What is the change of resistance?

4. (7 marks)

A dynamometer wattmeter has a deflection to current response given by:

DeflectionFull scale deflection

7500*ifim

If the resistance in series with the moving coil is 4000 ohms, what power will be delivered to the load when the meter is registering half-scale?

5. (8 marks)

Find the input resolution (the minimum voltage change that can be detected) of a DVM if the binary output of the ADC is 1011001100 when the input voltage is 3.58 volts.

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6. (6 marks)

The amplifier shown below has three stages, whose gains are shown as ratios. What would be the overall power gain of the system in decibels?

7. (10 marks)

A meter movement with a d.c. sensitivity of 1600 ohms/volt and 150 ohms resistance is used as an a.c. instrument by the addition of a series diode and resistor. An a.c. voltage of 10 volts peak-to-peak produces a full-scale deflection. What value of series resistance is required to achieve this?

8. (10 marks)

A thermistor, whose characteristics are shown below, has a resistance of 2000 ohms at 150 oC. It is connected in series with a resistor of 1600 ohms across a supply of 12 volts. What would be the voltages across the thermistor at temperatures of 100oC, 200oC and 300oC ? 1M

100K

10K

1K

100

10 -500100200300

o Temperature -C

END OF EXAMINATION PAPER

Thermistor resistance - ohms

山科大 高等电子测量 外语版

山东科技大学2009—2010 学年第一学期

《高等电子测量技术》考试试卷

班级 姓名 学号 SECTION A (Total marks 25)

Enter T (true) or F (false) against each of the following statements

51. Resolution is defined as the smallest change in the input that can be measured by

a system. [ ]

52. When finding the best-fit curve for readings from a wattmeter using Excel, we

choose a polynomial of order 2. [ ]

53. In rejection analysis, a set of 18 readings would put the rejection lines at +3 and

-3 [ ]

54. Boundary Scan is a method of measuring frequency response in analogue circuits.

[ ]

55. In a CAN network, the message with the lowest binary value will reach the

destination. [ ]

56. In automatic measurement the word “DUT” means “Don’t Use Today”. [ ] 57. A stepper motor with 4 coils and 50 teeth on the rotor would have a step angle of

3.6 degrees. [ ]

58. The output position of a digital servo is controlled by Pulse Width Modulation.

[ ]

59. In a laser printer there is a wire, near the transfer drum, which has a high positive

voltage. [ ]

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60. When a dot-matrix printer is connected to a computer, the ACKN line sends a

signal to the printer. [ ]

61. A Time Domain Reflectometer (TDR) can be used to measure the length of a

coaxial cable. [ ]

62. When a TDR receives a positive reflected pulse of the same amplitude as the

transmitted pulse, we know that there is a short-circuit on the cable. [ ] 63. The hybrid spectrum analyser uses a mixer and local oscillator to reduce the

signal frequency before it goes to the ADC. [ ]

64. Sweep frequency measurements enable us to determine the transfer function Hf

of an electronic circuit. [ ]

65. Jules Lissajous was a Swiss physicist. [ ]

66. Analogue storage oscilloscopes make use of the principle of secondary emission

of light. [ ]

67. The trigger pulses for an analogue oscilloscope timebase are derived from the Y

input through a Schmitt trigger. [ ]

68. The molecules in a liquid-crystal are rotated by 90o by means of a magnetic field.

[ ]

69. Common cathode 7-segment displays are switched on when the voltages on the

segment pins are high. [ ]

70. A successive-approximation converter uses a switch-tree to control one of the

voltages to the comparator. [ ]

71. The dual-slope integrating converter generates a positive ramp voltage for a fixed

number of clock cycles. [ ]

72. The dynamometer wattmeter contains two permanent magnets. [ ] 73. A power level of 17 dBm is equivalent to 30 mW. [ ]

74. For a.c. voltmeters, a full-wave rectified instrument will have twice the sensitivity

山科大 高等电子测量 外语版

of a half-wave rectified instrument. [ ] 75. The scale of an ohmmeter is logarithmic. [ ]

SECTION B (Total 15 marks)

Tick A, B, C or D in the following statements.

76. To eliminate Deviant Value Errors we use the method known as…

A [ ] Linear regression

C [ ] Averaging

B [ ] Rejection analysis D [ ] Best-fit line

77. A Bed-of-Nails tester is used to measure…

A [ ] ICs B [ ] Cable length C [ ] Polarisation D [ ] Circuit boards 78. The charging wire in a laser printer is used to…

A [ ] Clean the drum

C [ ] Dry the ink

B [ ] Heat the paper D [ ] Charge the drum

79. The total number of lines between a computer and a dot-matrix printer is…

A [ ] 11

B [ ] 8

C [ ] 16

D [ ] 4

80. A d.c. signal sent to a chart recorder will produce on the paper a…

A [ ] Circle B [ ] Straight line C [ ] Sine Wave D [ ] Nothing 81. A Short-Circuit at the end of a cable will produce a Reflection Coefficient of…

A [ ] 0 B [ ] 1 C [ ] -1

D [ ] 0.5

82. A digital spectrum analyser for the range 50 – 96 MHz requires a minimum

sampling frequency of…

A [ ] 100 MHz B [ ] 192 MHz C [ ] 48 MHz D [ ] 146 MHz 83. The Lissajous figure for the inputs X = sin At and Y = sin(At – 45o) is a…

A [ ] Straight line B [ ] Ellipse C [ ] Circle D [ ] Figure of eight 84. If the binary number 0101 is inputted to a 74LS47 decoder (for 7-segment

displays), the binary output from the decoder would be…

A [ ] 0100100 B [ ] 0011010 C [ ] 1011001 D [ ] 0001011

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85. An 11-bit ADC has a maximum input of 10 V. When the input is 3.3 V, the

output of the ADC is…

A [ ] 11000101110 B [ ] 01010100011 C [ ] 01000011111

D [ ] 01110101101

86. If the maximum input of a 9-bit ADC is 6 V, then the input resolution will be…

A [ ] 54.3 mV B [ ] 6.0 mV C [ ] 15.8 mV D [ ] 11.7 mV 87. The angle between the directions of the two polarisers in an LCD is.. A [ ] 0o B [ ] 45o C [ ] 90o D [ ] 180o 88. An amplifier has 3 stages with power gains of 100, 400 and 50 (ratios). The

overall power gain of the amplifier in decibels (dB) is…

A [ ] 57 dB B [ ] 47 dB C [ ] 63 dB D [ ] 73 dB 89. A meter movement has a Sensitivity of 1500 /V. To make a 0 – 200 V

voltmeter would require a total series resistance of…

A [ ] 1500 B [ ] 300 k C [ ] 75 D [ ] 550 k 90. A resistive strain gauge with sensitivity factor of 2 and initial resistance of 180

is strained by 1%. The change of resistance is…

A [ ] 3.6 B [ ] 1.8 C [ ] 7.2 D [ ] 2.0

SECTION C (Total 60 marks)

91. (5 marks) Design a circuit using op-amps with three inputs V1, V2, V3 and

output Vo having the following relationship:

Vo = 5V1 – 3V2 – 2.5V3

Use realistic values for the components.

92. (10 marks) A photo-diode has the characteristic curves shown below. It is

connected in series with a 200 resistor across a 0.4 V supply, which provides reverse bias.

(a) What will be the voltages across the diode when the light intensities are 1500, 10000, 20000 lm/m2.

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(b) For which light intensities will the device be photoconductive, and for which will it be photovoltaic.

-4

ID

-3

-2mA

-1

-0.5

-0.4

-0.3-0.2

-0.10

VD 0.1Volts

0.20.30.40.5

93. (5 marks) For the instrumentation amplifier shown below, what value of RGain

would be required to give a voltage gain of 50, if R = 20 k ?

VinVO

\

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94. (15 marks)

For the ADC shown above, do the following:

(a) Draw the waveforms (on the axes printed below) for Vramp and the voltages at G and X, showing the times clearly.

(b) Calculate the 8-bit binary number produced at Q7….Q0. (c) What will be the decimal numbers on the 7-segment displays?

(d) What is the maximum input voltage for which the ADC will operate correctly?

G

time

Vramp

time

X

time

山科大 高等电子测量 外语版

95. (5 marks) The diagram shows a digital

shaft encoder, where the black areas are at Logic 1 voltage, and the white at Logic 0. The shaft moves from its present position in 4a clockwise direction until Sector 6 is under the contacts. What will be the binary numbers outputted on connections C1..C3

5

during the movement?

(C1 is assumed to be the Most Significant Bit, MSB.)

32

C1C2C3

1

o

8

6

7

96. (5 marks) The Lissajous figure shown in the X

diagram is produced by two oscillators connected to the X and Y inputs of tan : Y = 3 : 2

oscilloscope. What is the ratio of the

Yfrequencies on X and Y?

t

Fig. 7.18 Frequency Ratio = 3:2

97. (5 marks) A power cable between Singapore and Malaysia has a length of 22

km, but has been broken by sabotage. A TDR connected to the Singapore end shows a large reflected pulse at 196 ms from the transmitted pulse. What is the distance of the break point from the Malaysian end of the cable? Relevant data: VOP of the cable = 0.50 Speed of light in vacuum = 2.998*108 m/s

98. (5 marks) The radioactivity readings shown in the table below were made in a

stable environment. Measurement errors obviously occurred, and the standard deviation was calculated to be 10.32.

It is suspected that deviant value errors may also have occurred.

i. Which values are deviant?

ii. After deleting the deviant values, what is the new average value?

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99. (5 marks) The depth of a lake was measured by ultrasonic means on two

different days. The readings are shown in the two tables below.

i. Calculate the mean value of the readings for each day. ii. Calculate the standard deviation for each day. iii. What types of measurement error have occurred?

END OF EXAMINATION PAPER

山东科技大学2007—2008 学年第1学期

《Electrical Measurements Practice Exam》考试试卷（ 卷）

班级 姓名 学号

SECTION A (Total marks 25)

Enter T (true) or F (false) against each of the following statements

100. When a voltage is measured it is called a direct measurement. [ ] 101. A transducer changes a physical quantity to an electrical quantity. [ ] 102. An oscilloscope is a indirect analogue indicating instrument. [ ]

103. A voltmeter with a pointer on a scale is an indirect analogue indicating instrument. [ ]

104. The gauge sensitivity factor of a strain gauge is (Resistive Strain)/(Mechanical

山科大 高等电子测量 外语版

Strain). [ ]

105. When the light on a photocell increases, the resistance also increases. [ ] 106. In the photovoltaic region a photo-diode can generate electricity. [ ] 107. A thermocouple can only measure up to 100oC. [ ]

108. If the temperature of a thermistor increases the resistance decreases. [ ] 109. The piezo effect in a crystal means that changes of voltage will produce changes of shape. [ ]

110. In an operational amplifier (op-amp) the current into the inputs is assumed to be very small. [ ]

111. The op-amp non-inverting circuit has a positive gain. [ ] 112. The op-amp integrator circuit does not require a switch. [ ]

113. The Schmidt trigger output can only have two states, either high or low. [ ] 114. An ammeter needs a series resistor. [ ]

115. Movement sensitivity = series resistance to make a voltmeter with 1 volt full-scale. [ ]

116. Sensitivity of a movement = 1/(Full-scale current). [ ] 117. An oscilloscope tube is filled with gas. [ ]

118. Electronic emission means electrons leaving the cathode. [ ]

119. The synchronisation circuit in an oscilloscope uses a Schmidt trigger. [ ] 120. The Lissajous figure for two sinewaves at 90o phase shift is a straight line. [ ] 121. In a common-cathode 7-segment display the positive voltage is applied to the cathode. [ ]

122. Analogue voltmeters have better accuracy than digital meters. [ ] 123. Plotters have three servo-motors. [ ] 124. Stepper motors do not move smoothly. [ ]

山科大 高等电子测量 外语版

SECTION B

(Total 25 marks)

Identify the labeled components on the diagram of the oscilloscope above by ticking A, B, C or D.

11. Component U:

A [ ] Grid B [ ] Anode C [ ] Cathode D [ ] Screen 12. Component V:

A [ ] Cathode B [ ] Phospor C [ ] Anode D [ ] Grid 13. Component W:

A [ ] Vertical deflection plate B [ ] Anode C [ ] Screen D [ ] Cathode 14. Component X:

A [ ] Anode B [ ] Vertical deflection plate C [ ] Grid D [ ] Cathode 15. Component Y:

A [ ] Grid B [ ] Anode C [ ] Horizontal deflection plate D [ ] Screen

SECTION C (Each question 10 marks. Total 50 marks)

3. A meter movement with a dc sensitivity of 1000 ohms/volt and 120 ohms

resistance is used as an ac voltmeter by the addition of a series diode and resistor. What value of series resistance is needed to produce a full-scale deflection for 12 volts rms?

4. An op-amp circuit has two inputs V1 and V2. Design the circuit to produce an

output given by: Vo = 3*(V2 – V1) Show the values of the resistors used. 3.

山科大 高等电子测量 外语版

A photo-transistor has the characteristics shown above. A 3 k resistor is connected in series with this photo-transistor across a 25 volt supply. What will be the values of the voltages across the transistor when the light intensities are 0, 200 and 400 watts/m2. 4.

The op-amp integrator circuit shown above has the following component values:- Ri = 1000 ohms C = 1 mF

The voltage Vin is fixed at +10 volts, and the switch is opened. What will be the value of Vo after 1 ms?

5. A dynamometer wattmeter has a deflection to current equation given by:

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