問題一覧
1
What gain is significant when an op-amp is used as a voltage comparator?
open-loop gain
2
A full 360 deg sine wave signal is applied to an unknown class of amplifier. If the output delivers only a pulse of less than 180 deg, what class does this amplifier belongs?
class C
3
Which of the following is false, concerning air cores versus ferromagnetic cores?
air concentrates the magnetic lines of flux
4
The input resistance of a common-base amplifier is
very low
5
The purpose of the I layer in a PIN diode is to
minimize the diode capacitance
6
Find the half-power bandwidth of a parallel resonant circuit which has a resonant frequency of 8.1 MHz and Q of 150.
54 kHz
7
How are the networks able to transform one impedance to another?
Resistance in the networks substitute for the resistances in the load.
8
The operating frequency of a Wien-bridge oscillator is given by ___.
1/2piRC
9
A diode limiter circuit
can cause objectionable signal distortion
10
Simple current limiting produces too much heat in
Pass transistor
11
An elementary generator consists of a single coil rotating in a magnetic field. Why is no voltage induced in the coil as it passes through the neutral plane?
Flux lines are not being cut
12
How many NAND-gates are required to form an OR-gate?
3
13
What direction is the magnetic field about a conductor when current is flowing?
in a direction determined by the left hand rule
14
In a linear regulator, the control transistor is conducting
all of the time
15
What is the ripple frequency of a half-wave rectifier with an input line frequency of 60 Hz?
60 Hz
16
A radio equipment will be used to 70% at 50 amperes rating fo 5 hours, how much capacity of dry battery is needed?
175
17
Which of the following amplifiers is considered linear?
either class A or B
18
What are the two basic categories of industrial robots?
pick and place manipulator and intelligent robot
19
How do you determine if diode is effective?
diode resistance is either very high or very low in either direction
20
A JFET always operates with
the gate-to-source pn junction reverse-biased
21
If a sine wave voltage varies from 0-200 V, how much is its instant voltage at 90 degrees?
200 V
22
The power dissipated in the core due to hysteresis and eddy current losses
iron loss
23
In an LC oscillator, if the value of L is increased four times, then frequency of oscillations is ____.
decreased two times
24
Which type of the following oscillator types uses transformer coupling to feed back a portion of the signal voltage. It is sometimes called a “tickler” coil.
Armstrong circuit
25
Voltage that is present at the output of an operational amplifier with its two inputs grounded.
output offset voltage
26
What is the purpose of the emitter capacitor?
to avoid drop in gain
27
A bubble memory is best suited for:
a large computer
28
An integrated circuit for both astable and monostable applications
555 timer
29
_____ is a measure of consistency of measurements.
precision
30
One of the following items below is not one of the main components of an alternating current power supply.
Rectifier
31
When an armature opens in dc motor, it may cause
intermittent sparking
32
If Ic is 50 times greater than IB, then βDC is
50
33
Flux linkage equals
flux times number of turns
34
With respect to memory, which of the following terms means that the data contents vanish if power is removed from a chip?
volatility
35
Combination of ac motor, dc generator, and exciter to provide adjustable voltage dc power to a dc motor.
ward-leonard system
36
A significant advantage, in some situations, of a toroidal coil over a solenoid is the fact that
the magnetic flux in a toroid is practically all within the core
37
A device used to mechanically measure the output power of a motor
dynamometer
38
Electrical classification of materials having 8 electrons.
insulator
39
Each stage of a four-stage amplifier has a voltage gain of 15. The overall voltage gain is
50,625
40
Which statement is wrong regarding μA741 when its supply voltage is increased?
large variation in the input offset voltage
41
In an NPN circuit, the collector
is positive with respect to the emitter
42
The ideal internal resistance of an emitter should be
zero
43
If the base-emitter junction is open, the collector voltage is
Vcc
44
What is the maximum efficiency of a full-wave center-tapped rectifier?
81.2%
45
This type of electrical machine is used for varying the input voltage into a higher or lower potential without changing the power transferred.
transformer
46
Low sensitive DC voltmeter provides inaccurate result when measuring ____ circuits.
high resistance
47
An AC bridge that measures inductance in terms of resistance and capacitance.
Owen’s bridge
48
The closed-loop voltage gain of an inverting amplifier equals
The feedback resistance divided by the input impedance
49
The output of an OR gate will be low if
all inputs are LOW
50
A manufacturer quotes in his specifications that a silicon diode conducts 50 mA at 1 V. Determines its bulk resistance.
6 ohms
51
Type of waveform generated by the sweep generator of the CRT
sawtooth
52
The regulator with the highest efficiency is the
switching regulator
53
A monopulse receiver has how many separate channels?
three
54
.Suppose you have an unlimited supply of 1-W, 1000-Ω resistors, and you need a 500-Ω resistance rated at 7 W or more. This can be done by assembling
four sets of two resistors in series, and connecting these four sets in parallel
55
If a power supplies 30 V with no load and 20V under full load, what is the percentage regulation?If a power supplies 30 V with no load and 20V under full load, what is the percentage regulation?
50%
56
Process of repairing the ruptured crystal structure caused by ion implantation by heating.
annealing
57
Capacitors are used to store data in
none of the above
58
Amplifier of low-level signals that provides an output that is an accurate multiple of the difference between two input signals
instrumentation amplifiers
59
The main problem with a bar-graph meter is that:
it can’t give a very precise reading
60
Air works well as a dielectric mainly because it
has low loss
61
If bandwidth increases, the
Q decreases
62
the dc output of a bridge type circuit is__ that of equivalent center tapped circuit.
more than
63
Which of the following is not an internal digital IC fault?
poor solder connections
64
Type of feedback employed in oscillators
positive
65
Result obtained when a 1 is added to the least significant bit position of a binary number in the 1’s-complement form
2’s complement
66
When a closed-loop system is used to maintain physical position it is referred to as
servo system
67
Which of the following is not a characteristic of CMOS chips?
ability to handle extremely high power
68
Small microcomputer used as a dedicated controller for a machine, a piece of equipment, or a process.
Microcontroller
69
What is the normal resting state of the SET and CLEAR inputs in a NAND gate latch?
SET=1, CLEAR=1
70
Class of programmable logic devices wherein its AND array is programmable while its OR array is hard wired.
PAL
71
The approximation with a maximally flat passband is
Inverse chebyshev
72
Which of the following robot drive mechanism is the cheapest to buy but has a limited payload?
pneumatic
73
In constructing transformers, the primary and secondary windings should have
tight magnetic coupling
74
The number of digits used by a number system.
radix
75
The energy of an oscillator can be sourced by
capacitance of inductive coupling from the tuned circuit
76
It is a robot structure wherein the body can pivot vertically and horizontally and that arms move radially
polar structure
77
How many major lobes are produced by a paraboloid reflector?
one
78
A meter when ___ damped will become insensitive to small signals.
overdamped
79
Situation when a circuit’s output level for a given set of input conditions can be assigned as either a 1 or 0.
don’t care
80
A Schmitt trigger is used to provide
A short duration pulse
81
Power source that converts desired electricity to the other.
motor set
82
If a 175-V dc source were connected in series with the utility mains from a standard wall outlet, the result would be
fluctuating dc
83
The input offset current is usually
less than the input bias current
84
The absolute maximum rating for op-amps interval power dissipation is
500mW
85
What is the typical slew rate of Fairchild 741 op-amp?
0.5 V/us
86
The typical saturation flux density for most magnetic materials.
2 Wb/m2
87
A digital circuit that oscillates between two unstable output states.
astable multivibrator
88
In a linear op-amp circuit, the
Op-amp does not go into saturation
89
Where do you classify cobalt as material?
Ferromagnetic
90
The bandwidth of a multistage amplifier is ___ that of a single stage amplifier.
less than
91
What are the primary methods of controlling electrical power?
all of the above
92
A summing amplifier can have
Two or more input signals
93
Electron flow assumes charges flow from
negative to positive
94
A pulsating dc applied to power amplifiers causes
hum in the circuit
95
A digital computer used for the automation of industrial processes, such as control of machinery or factory assembly lines
PLC
96
Suppose a purely resistive impedance of 75 Ω must be matched to a purely resistive impedance of 300 Ω. A quarter-wave section would need to have
Zo=150 Ω
97
How many cells would a 16 word x 6 bit memory contain?
96
98
Which of the following is not a general characteristic of an ac wave?
the electrons always flow in the same direction
99
The device used to use for rectifying a weak ac signal is a
Back Diode
100
A frequency synthesizer has
exceptional stability