Engineering ETA

Electrostatic Discharge

1. What does the acronym ESD stand for?

voltage, current and resistance.

10. An analog multimeter (AMM) checks for:

Cathode

100. In a common anode, seven-segment LED display, an individual LED will light if a negative voltage is applied to what element?

dual-trace

11. An oscilloscope with two vertical inputs, is commonly referred to as a _______ oscilloscope.

voltage drop.

12. Voltage or potential difference is the measure of potential energy between two points in a circuit and is commonly referred to as:

The resistance of a component at a given frequency

13. What is impedance?

210 Ohms

14. A resistor has three color bands of red, brown and brown. What is the ohmic value of this resistor?

Inductor

15. What components value is measured in millihenries?

power, resistance, current and voltage.

16. Ohm's Law characterizes the relationship between:

Voltage times current

17. Ohm's Law states that resistance is calculated by voltage divided by current. Using Ohms law, how do you determine power?

3.3 * 10^3.

18. Using a scientific calculator, a 3300 ohm resistor can be entered with scientific notation as:

the sum of all the resistor values within the circuit.

19. Total resistance in a series circuit equals:

100mA, 200mA -Explanation: Though currents between 100mA and 200mA can kill a human being, if resuscitation is available, chances for survival are 80- 90%.

2. Current amounts between ______ and _____ can be lethal.

333.33uA

20. If a series circuit has three resistors valued at 10k Ohms, 15k Ohms and 20k Ohms, with a voltage source of 15V, the total current will be_____.

inversely proportional to the circuits resistance.

21. Current in a parallel circuit is:

669.29 Ohms

22. With three 2.5k resistors and one 3.4k resistor in parallel, the total resistance is:

20 Ohms

23. With one series 8 Ohm resistor connected to two in-parallel resistors, 20 and 30 ohms respectively, what is the total resistance (Rt)?

50

24. Given a battery rated at 350 ampere-hours how many hours will the battery be able to provide 7 amperes?

2A

50. In the circuit below, what is the current across R2?

1.86V

51. What is the voltage at terminal 'A' for the Wheatstone bridge below?

Vout = (R2/R2+R1) * Vin

52. What formula is used to properly calculate 'Vout' for the voltage divider below?

75.75 ohms Explanation: Understanding Question Number 53 on the AST Practice Exam Let's get started by realizing there are a myriad of ways to calculate the value for R2. We are going to look at finding the value of R2 and using the value of R2 for determining and proofing in three distinct calculative methods. The first method will use a industry standard of 10%, which will be explained as we move into the method. The second method will show the circuit redrawn with the resistive values and voltage source value in place, but nothing else. The third method will use the redrawn circuit but only R1, R3-not R2- and the voltage source values will be given. Method #1 Using the schematic below for question #53 on the AST Practice Exam, let's now calculate R2 1. First, we need to take inventory of what we have been given: · Voltage = source voltage = ES = 100 Volts · Load voltage = ELoad = 25 Volts; also known as ER1 · Load current = I Load = 900mA 2. Now calculate current across R1. To do this you need to use the 10% electrical engineering rule for loaded voltage dividers that I mentioned above. This is a simple assumption of current that, when used by the other two proofs, is seen to be viable and correct: · IR1 = 10% * I Load · IR1 = .1 * .9mA · IR1 = .09A or 90mA 3. Using the newly found value of IR1 = .09A, calculate resistance for R1. It is realized we have this, but this is done to ensure proper calculations. This is also known as our calculation for bleeder resistance since this is the bleeder resistor: · R1 = E R1 / I R1 · R1 = 277.77 Ohms or rounded it will equal 278 Ohms; I stayed with 277.77 Ohms 4. Using I R1 added to our load current the total current for the circuit, also known as bleeder plus load current is: · IT = ILoad + IR1 · IT = .9 + .09 · IT = 990mA 5. Though we can assume the voltage across R2 = 75V, it is better to calculate to ensure proper values: · ER2 = ES - ER1; Remember our load voltage is also known as our voltage across R1; parallel circuit calculation. · ER2 = 100 - 25 · ER2 =75V 6. And now with all the pertinent values behind us we can calculate the value for R2: · R2 = E R2 / IT · R2= 75/.990 · R2 = 75.75 Ohms That is how to calculate R2 using the first method utilizing the EE 10% rule. Now let's look at method #2 Method #2 In this method we are given resistance values, thus we will use our formulas and calculations to ensure method #1 is correct. Using our redrawn schematic for question #53 on the AST Practice Exam below, let's begin. mc053-3.jpg 1. Once again, we need to take inventory of what we have been given: · Voltage = source voltage = ES = 100 Volts · R1 = 277.77 Ohms · R2 = 75.75 Ohms; calculated from method #1 Note: The value for R3 is calculated from method #1; ER3 / IR3 = R3; 25/.9 = 27.77Ohms · R3 = 27.77 Ohms 2. First, let's calculate Req given R1 and R2. This will effectively make our circuit a series circuit (View Schematic below for Req) mc053-4.jpg · Req = 1/((1/ R1) + (1/ R3)) · Req = 25.246 Ohms 3. Now with Req added to R2 we can arrive at our total resistance for the circuit: · RT = 25.246 + 75.75 · RT = 100.996 Ohms 4. Let's now calculate total current in our series circuit: · IT = ES / RT · IT = 100 / 100.996 · IT = .990A or 990mA. This is the same amperage found in method #1, para. #4. 5. With our new found total current we can now start calculate the voltage across R2. · ER2 = IT * R2 · ER2 = .990 * 75.75 · ER2 = 74.99 -> rounded = 75 volts, which is correct. 6. In a parallel circuit the voltage across ER1 and ER3 is equal to one another. With that being true then ES - ER2 = 25 volts for ER1 and ER3; This is correct as in method #1's given values. 7. To finalize this proof, let's calculate current for ER1 and ER3. · IR1 = ER1 / R1 · IR1 = 25/277.77 · IR1 = .09A or 90mA -> 10% of R3 load current as in method #1 · IR3 = ER3 / R3 · IR3 = 25/27.77 · IR3 = .9A or 900ma load current as in method #1 That is how to proof method #1. Now let's look at our final method, method #3. This time we are not given any values for R2. We will have to use values calculated from ER1 and ER3. By using the following schematic, let's finalize our proofing with method #3. mc053-5.jpg 1. We need to take inventory of what we have been given: · Voltage = source voltage = ES = 100 Volts · R1 = 277.77 Ohms · R3 = 27.77 Ohms 2. Since we have already calculated Req we will not do this again; Req = 25.246 Ohms. 3. Knowing from method #2 the voltage across each parallel branch is 25volts, that leaves us to realize the voltage, given an ES = 100V, across R2 = ER2 = 75V. 4. Now we can calculate IT · IT = IR1 + IR3 · IT = 09A + 9A · IT = 990mA 5. Now that we have IT and know voltage across R2, we can calculate the resistance value R2. · R2 = ER2 / IT · R2 = 75 / 990mA · R2 = 75.75 Ohms, which proofs method #1 and #2.

53. In the circuit below, what is the value of R2?

High input impedance

54. What is a primary advantage of a FET when compared to the bipolar transistor?

reverse

55. Zener diodes are designed to operate in the _____ bias region.

Gate

56. When compared to a JFET, the base of a bipolar transistor is similar to what element of the JFET?

Gate, source, drain and substrate

57. A MOSFET is comprised of what four elements?

One

58. How many PN junctions does a Unijunction transistor have?

Common base

59. Which bipolar transistor configuration has a current gain of less than 1?

Conductors, semi-conductors and insulators

6. What are three types of materials used in electronics?

4,3

60. A thyristor is a semiconductor with _____ layers that form ____ PN junctions.

979.93 ohms

61. Calculate total impedance for the circuit below.

4.7V Explanation: Vc = i × Xc; then to proof total Voltage: V=sqrt((VL- Vc)² + Vr²)

62. Calculate the voltage drop across C1.

5A

63. What is Iz for the circuit below?

dB=10*log(P1/P2)

64. When calculating power levels, which formula is correct?

50%

65. If a signal decreases by 3 dB, how much power is lost?

.5mW

66. -3dBm is equal to how many milliwatts?

10 log10( P / 1mW)

67. The formula to calculate dBm from mW is:

regenerative feedback.

68. The split capacitors in a Colpitts oscillator provide:

When keeping frequency error or drift at a minimum is important

69. Why are crystal oscillators preferred over other types of oscillators?

A, B, C, D, K.

7. In the United States there are five common classifications of fires, which are:

75 kHz

70. What is the resonant frequency for the circuit below?

To produce a sharp spike

71. Why is a differentiator used at the input of a flip-flop?

Place a swamping resistor across the transformer

72. What is one way to minimize parasitic oscillations?

collector current flows for less than one half cycle of the input signal.

73. In a class 'C'collector:

16

74. What is the radix of the hexadecimal number system?

26E

75. What is the hexadecimal equivalent of the decimal number 622?

43

76. What is the decimal sum of 10010 and 11001?

NOR

77. What is the digital gate equivalent for the circuit below?

A

78. Which truth table is correct for the following logic diagram?

Electrically Alterable Read Only Memory

79. What does the acronym EAROM stand for?

directly proportional, inversely proportional

8. Coulomb's Law describes the forces of attraction or repulsion between electrical charges, which are ______________ to the product of the charges ______________ to the distance between them.

Arithmetic logic, interfacing and control

80. What are three processor functions of a CPU?

1.6 microseconds

81. If an oscilloscopes TIME/DIV is set at .2 microseconds, and the width of the pulse measured is at 8 divisions on the scope graticule, what is the pulse width?

50

82. The coaxial cable leading to a cable TV is a 75 ohm transmission line. If you use 10Base2 coax cable for networking, that is a _____ ohm transmission line.

To prevent the formation of metal oxides at extreme temperatures

83. Why is flux used when soldering?

361o F.

84. Lead and tin solder at a respective percentage of 63/37 melts at ______:

Direct, RC, impedance and transformer coupling

85. What four methods are used in coupling amplifier stages?

Vout = (Rf/Rin)(V2 - V1)

86. What formula is used to calculate output voltage of a Difference operational amplifier?

Pi, capacitive, inductive

87. Due to the configuration of the filtering components, the ability of a_____ type filter to remove ripple voltage is superior to that of either the _______ or ________ filter.

Schematic

88. What type of diagram shows electrical connections and functions of a specific circuit arrangement?

7,000V

89. Opening and closing vinyl envelopes used to carry work instructions, with 10-20% relative humidity, electro-static voltages can reach as high as:

lines of flux.

9. The magnetic field that surrounds a magnet can best be described as invisible lines of force, and are commonly referred to as:

32

90. What is the modulus of a five-stage binary counter?

Motorized vacuum extraction

91. What is the preferred method for removing solder from a component attached to a circuit card assembly (CCA)?

time-division multiplex

92. To overcome noise, distortion and cost of maintenance in frequency division multiple systems, ________ systems were developed.

Local exchange carrier

93. What does LEC stand for?

one

94. Circuit switch networks maintain only _____ path(s) for the duration of the call.

shells

5. Electrons are arranged in _____ around a nucleus.

frequency, period, wavelength and amplitude. Ex:Amplitude is the max displacement of the wave's oscillation; voltage level · Period is when one cycle is measured in a unit of time, most often seconds or fractions of a second. When expressed as a measurement, this is often called the period of a wave. The period of a wave in degrees is always 360, but the amount of time one period occupies depends on the rate voltage oscillates back and forth; negative and positive alternations · Wavelength is the distance a waveform covers during a set period. · Frequency is the number of cycles of ac per second. AC frequency is measured in hertz.

25. The basic properties associated with alternating voltage and current are:

5.48V

26. What is the calculated effective voltage for the wave form below?

250Hz

27. What is the frequency of the sine wave below?

Dielectric

28. In the illustration below, what component of the coaxial cable is the letter "B"?

Square

29. In an inductor/coil inductance varies as the _______ of the number of turns.

Shock

3. What is the number one concern in regards to electrical safety?

4.24H

30. What is the total inductance of the circuit below?

signal matching and power supplies.

31. Two basic uses for transformers are:

The transfer of energy from one circuit to another circuit by electromagnetic induction

32. What is meant by "transformer action"?

Primary winding, secondary winding and core

33. What are the three basic parts of a transformer?

10V

34. In the circuit below, what is the voltage output at letter "X", when input voltage is 25V?

a time constant.

35. The time required to charge a capacitor to 63 percent is known as:

.008uF

36. Given the series capacitive circuit below, what is the total capacitance?

40.21 Ohms

37. Calculate the capacitive reactance for 440 Hz and 9µF.

90 degree

38. In a resistive-capacitive circuit the vector line relationship shows two lines perpendicular to each other. What is the phase relationship?

Voltage lags

39. In a capacitive circuit, what is the voltage and current relationship?

Protons, neutrons and electrons

4. Bohr's Atomic Model consists of what three components?

decrease.

40. When the frequency of an applied voltage is increased the capacitive reactance of a circuit will:

A series impedance calculation is derived from resistance and reactance, while parallel impedance is calculated with resistive and reactive current divided into the source voltage

41. What is the difference between calculating impedance for a series AC circuit and a parallel AC circuit?

characteristic impedance

42. Each type of coaxial cable is designed with_____________, which is dependent on materials and dimensions used.

Dielectric constant and permeability

43. A coaxial cable's velocity of propagation factor depends on what two factors?

Z =sqrt( R2 + X2)

44. In a series resistive and reactive circuit what formula is used to find total impedance?

.7V

45. Silicon diodes have an approximate voltage drop of:

E = -1; B = +1; C = +10

46. To properly bias the NPN transistor below, which voltages are correct?

16 AWG

47. In regards to AWG standards, which gauge of wire has a bigger cross-sectional area?

166.6 mW

48. Using ohm's law for the circuit below, calculate the total power.

43.2W Explantion: Calculated power for R3 - PROOF: 1. The circuit must first be realized as a series parallel DC circuit. 2. Given data: · Et=60 · R1 = 8W · R2 = 20W · R3 = 30W 3. First, combine R2 and R3 to calculate Req. This can be done, but not limited to, two ways: · (R1*R3)(R2+R3)=Ohms; (20*30)(20+30) = 600¸50 = 12W · 1¸(1/R2)+(1/R3)=Ohms; 1¸(1/20+1/30) = 1¸(5/60) = 60/5 = 12W 4. Req = 12W 5. Next add R1 and Req to calculate Rt · Rt = 8W + 12W = 20W; Rt = 20W 6. Next, divide the total voltage (Et) by total resistance (Rt) to find the total Current (It). Et¸Rt = It · 60 ¸ 20 = 3; It = 3 amps 7. Now we must account for the voltage drops and current for the entire circuit. · To find the voltage drop for R1 (ER1) we need to multiply the current by the Ohms for the resistor for which we want to find the voltage: 3*8 = 24 volts. ER1 = 24 volts. · To find the voltage drop for Req, there are two ways to realize this: o One way is to take the 24v of ER1 and subtract it from Et, which is 36v. 60-24 = 36 o Second way is to multiply the current by the Ohms for the resistor for which we want to find the voltage: 3*12 = 36 volts 8. Since the voltage drop across a parallel circuit is the same for all branches/resistors, let's find the current flow for each resistor within the parallel branches. 9. Remember I = E ¸ R. Therefore, ER2 ¸ R2 = IR2 and ER3 ¸ R3 = IR3 · ER2 ¸ R2 = IR2. 36 ¸ 20 = 1.8 amps. IR2 = 1.8A · ER3 ¸ R3 = IR3. 36 ¸ 30 = 1.2 amps. IR3 = 1.2A 10. With the information above we can now calculate for power (wattage) for R3 {question 49}. There are three ways to do so: · P = IR3 * ER3; 1.2 * 36 = 43.2 watts(W) · P = ER32 ¸ R3; 1296 ¸ 30 = 43.2 W · P = IR32 * R3; 1.44 * 30 = 43.2 W

49. In the circuit below, what is the calculated power for R3.

FDMA, CDMA and TDMA Explanation: J. Baldwin: GSM is a type of TDMA, which has replaced what we once called IS-136 spec which was routinely called TDMA, but as far as the basics, it is correct to call these three access technologies. LTE and all of the other new derivatives today, WCDMA, UMTS, HSDPA etc,... are still an offshoot of these basic types. 3G and 4G improvements, that we hear on the news everyday are more for wireless data that voice, and employ new coding or modulation types.

95. What are the three fundamental types of wireless access technologies?

current, amplitude

96. In the kinescope, the ________ intensity of an electron beam from an electron gun is modulated in accordance with the ________ variations of signals received by a

90 degrees

97. An electromagnetic wave is composed of an electromagnetic and electric field, which are at ______ from one another.

90 degree

98. A vertically polarized antenna has a magnetic field that is at a _____ angle to the axis of the antenna.

70 MHz

99. The 4-meter frequency band is also known as the _____ band.