Section B
Chapter 3
1 One of the following is not a conductor:
a. Silver.
b. Aluminum.
c. Copper.
d.* Mica.
2 One of the following is not an insulator:
a. Mica.
b. Ceramic.
c. Plastic.
d.* Copper.
3 The opposition to the flow of current in a circuit is
called:
a.* Resistance.
b. Inductance.
c. Emission.
d. Capacitance.
4 A potentiometer is a :
a. Meter.
b.* Variable resistor.
c. Battery.
d. Capacitor.
5 The current through a 100 ohm resistor is to 120mA. What
is the potential difference across the resistor?
a. 120 volt.
b. 8,33 volt.
c. 83,33 volt.
d.* 12 volt.
6 The resistance value of 1200 ohms can be expressed as:
a. 12 kilo ohms.
b.* 1,2 kilo ohms.
c. 1,2 Mega ohms.
d. 0,12 Mega ohms.
7 How can the current be calculated when the voltage and
resistance
in a dc circuit is known?
a.* I = E / R.
b. P = I x E.
c. I = R x E.
d. I = E x R.
8 A 12 volt battery supplies a current of 0.25-ampere to a
load.
What is the input resistance of this load?
a. 0.02 ohm.
b. 3 ohm.
c.* 48 ohm.
d. 480 ohm.
9 If 120volt is measured across a 470 ohm resistor,
approximately
how much current is flowing through this resistor?
a. 56.40 ampere.
b. 5.64 ampere.
c. 3.92 ampere.
d.* 0.25 ampere.
10 How can you determine a carbon resistor's electrical
tolerance rating?
a. By using a wave meter.
b.* By using the resistor's color code.
c. By using Thevenin's theorem for resistors.
d. By using the Baudot code.
11 What causes resistors in an electrical circuit to
increase in temperature?
a.* Power Dissipation.
b. Stray lead inductance.
c. The Siemens factor.
d. Kirchoff's law.
12 Two resistors are connected in series. The combined
resistance is 1200 ohm. If one of the resistors is 800
ohm, what is the value of the other?
a. 1000 ohm.
b. 800 ohm.
c.* 400 ohm.
d. 1200 ohm.
13 Two 10 kilo ohm resistors are connected in parallel. If
the voltage from a battery across the resistors sets up a
current of 5mA in the one resistor, how much current flows
in the second?
a. 10 mA.
b. 2 mA.
c. 20 mA.
d.* 5 mA.
14 In a parallel circuit with a voltage source and several
branch resistors, what relationship does the total current
have to the current in the branch currents?
a. The total equals the average of the branch current in
each resistor.
b.* The total equals the sum of the branch currents in
each resistor.
c. The total decreases as more parallel resistors are
added to the circuit.
d. The total is calculated by adding the voltage drops
across each resistor and multiplying the sum by the total
number of all circuit resistors.
15 Which of the resistors below (each identified by its
color coding) would be nearest in value to a 4k7 resistor?
a. Orange violet orange.
b.* Yellow green red.
c. Orange violet red.
d. Yellow green orange.
6 A light bulb is rated at 12 volt and 3 watt. The current
drawn when used on a 12 volt source is:
a.* 250 mA.
b. 750 mA.
c. 4 A
d. 36 A
17 A light bulb draws 0,5 A from a 12 V battery when lit.
How much power does it consume?
a. 3 W.
b.* 6 W.
c. 0,03 W.
d. 24 W.
18 The DC current drawn by the final stage of a linear
amplifier is 100 mA at 100 V. How much power is consumed?
a. 100 watt.
b. 1 kilo watt.
c.* 10 watt.
d. 1 watt.
19 If a power supply delivers 200 W of electrical power at
400 V DC to a load, how much current does the load draw?
a.* 0.5 A.
b. 2.0 A.
c. 5 A.
d. 80,000 A.
20 A transmitter's pilot light is connected to 12 volt DC
and draws 0.2 ampere. How many watt of electrical power
are being consumed?
a. 60 watt.
b. 24 watt.
c. 6 watt.
d.* 2.4 watt.
21 The product of the current and what force gives you the
electrical power in a circuit?
a. Magnetomotive force.
b. Centripetal force.
c. Electrochemical force.
d.* Electromotive force.
22 A 10 ohm resistor is dissipating 40 watt power. The
current flowing is:
a. 16 A
b. 2 A.
c.* 4 A.
d. 250 mA.
23 A resistor is rated at 10 watt. Which of the following
combinations of potential difference and current exceeds
the rating of the resistor?
a. 2V, 100 mA.
b. 20V, 200 ?A.
c.* 1 kV, 25 mA.
d. 10 mV, 2 A.
24 A resistor has a potential difference across it of 16 V
and is carrying a current of 20 mA. It is dissipating heat
at a rate of:
a. 3.2 W.
b.* 0.32 W.
c. 0.8 W.
d. 0.08 W.
25 Which value represents the ratio of RMS to Peak value
of an AC waveform?
a. 0.5
b. 0.636
c. 1.414
d.* 0.707
26 Which value represents the ratio of Average to Peak
value of an AC waveform?
a. 0.5
b.* 0.636
c. 1.414
d. 0.707
27 As what is the value of an AC waveform, representing
the equivalent heating effect to a DC voltage, known as ?
a.* RMS value .
b. Average value.
c. Peak value.
d. Corrected value.
28 Two 500 pF capacitors in series produce an equivalent
capacitance of
a. 1000 pF.
b. 2000 pF.
c.* 250 pF.
d. 1 nF.
29 Three capacitors of 1 ?F are connected in parallel. The
equivalent capacitance is:
a. 0,33 ?F.
b.* 3,0 ?F.
c. 0,3 ?F.
d. 33,33 ?F.
30 A capacitor of 250 pF is required to resonate a tuned
circuit. A 100 pF capacitor is connected in parallel to a
variable capacitor. What value must the variable capacitor
be set to achieve resonance?
a.* 150 pF.
b. 300 pF.
c. 350 pF.
d. 400 pF.
31 A value of 1000pF is equal to:
a. 10nF.
b.* 1nF.
c. 0.1nF.
d. 100nF.
32 The energy in a charged capacitor is stored in the:
a. Voltage across the terminals.
b. Current applied to the capacitor.
c.* The electric field between the plates.
d. Form of magnetism.
33 The unit of capacitance is called ?
a.* Farad.
b. Permeability.
c. Conductance.
d. Impedance.
34 What is the total capacitance of two or more capacitors
connected in parallel?
a. The same as either capacitor.
b. Half the capacitance of either capacitor.
c. Twice the capacitance of either capacitor.
d.* The capacitance cannot be determined without knowing
the exact values of the capacitors.
35 What do the units microfarad and picofarad specify?
a. Inductance.
b.* Capacitance.
c. Resistance.
d. Current.
36 A microfarad equals how many farads?
a. 0.001 F
b.* 0.000,001 F
c. 0.000,000,001 F
d. 0.000,000,000,001 F
37 As the plate area of a capacitor increases, its
capacitance:
a. Decreases.
b.* Increases.
c. Stay the same.
d. Becomes voltage dependent.
38 What does an electrolytic capacitor contain?
a. Carbon terminals.
b. Oil and mica.
c.* Aluminum foil and chemical insulation.
d. A semi liquid conducting chemical.
39 Which part moves in a typical variable capacitor?
a. Both sets of plates.
b. A ferrite rod.
c. Mica strips.
d.* Only one set of plates.
40 Which of the factors below would NOT influence the
capacitance value of a capacitor?
a. Area of the plates.
b. Distance between the plates.
c.* Voltage rating.
d. Di-electric constant of the material between the
plates.
41 The unit of Inductance is called:
a. Ohm.
b. Resonance.
c.* Henry.
d. Impedance.
42 Movement of a magnetic field induces what into a
closely coupled coil of wire?
a.* A voltage.
b. Movement of the coil.
c. Inductance.
d. Mutual inductance.
43 Two different coils in close proximity possess:
a. Parallel circuits.
b. Equal impedances.
c.* Mutual inductance.
d. Resonance.
44 The characteristic back-EMF which a collapsing magnetic
field causes in a coil is called:
a. Mutual inductance.
b.* Self inductance.
c. Magnetic flux.
d. The solenoid effect.
45 What is the unit of inductance?
a.* The Henry.
b. The coulomb.
c. The farad.
d. The ohm.
46 A small air-core coil has an inductance of 5 microhenry.
What do you have to do if you want a 5 millihenry coil
with the same physical dimensions?
a. The coil must be wound on a non-conducting tube.
b.* The coil must be wound on an iron core.
c. Both ends of the coil must be brought around to form
the shape of a doughnut, or toroid.
d. The coil must be made of a heavier-gauge wire.
47 For radio frequency power applications, with which type
of inductor would you get the least amount of loss?
a. Magnetic wire.
b. Iron core.
c.* Air-core.
d. Slug-tuned.
48 In an inductive circuit, the alternating current
produced in relation to the applied EMF is:
a.* Lagging by 90 degrees.
b. 180 degrees out of phase.
c. Leading by 90 degrees.
d. In phase.
49 The frequency of an AC waveform is defined in the unit:
a. Seconds.
b. Velocity.
c. Period.
d.* Hertz.
50 The frequency of 5 Hz has a period of:
a. 2 seconds.
b. 300 seconds.
c.* 0.2 seconds.
d. 1.2 seconds.
51 The phase shift between voltage and current in a
capacitor is:
a.* 90 degrees.
b. 45 degrees.
c. 360 degrees.
d. In phase.
52 The phase shift between voltage and current in an
inductor is:
a.* 90 degrees.
b. 45 degrees.
c. 360 degrees.
d. In phase.
53 The reactance to AC current flow in a coil or capacitor
is measured in:
a. Energy units.
b. Watt.
c.* Ohm.
d. Q.
54 The reactance of an inductor:
a. Remains constant with changing frequency.
b.* Increases with increasing frequency.
c. Decreases with increasing frequency.
d. Increases with decreasing frequency.
55 The reactance of a capacitor:
a. Remains constant with changing frequency.
b. Increases with increasing frequency.
c.* Decreases with increasing frequency.
d. Increases with decreasing frequency.
56 What is the unit measure of impedance?
a.* Ohm.
b. Volt.
c. Ampere.
d. Watt.
57 What is the unit measure of impedance, reactance and
resistance called?
a. Mho.
b.* Ohm.
c. Ampere.
d. Siemen.
58 What is the opposition to the flow of an alternating
electrical current in a circuit containing both resistance
and reactance called?
a. Ohm.
b. Joule.
c.* Impedance.
d. Watt.
59 The capacitive reactance of a 16 ?F, 40 volt working
electrolytic capacitor to a signal of 100 Hz is:
a. 1 000 ohm.
b. 10 K ohm.
c. 10 ohm.
d.* 100 ohm.
60 If the alternating frequency applied to a capacitor is
doubled, the capacitor’s capacitive reactance will be:
a. doubled.
b. four times original value.
c. one quarter the original value.
d.* halved in value.
61 At one particular frequency, resonance of a capacitor
and inductor takes place. At this frequency:
a. Inductive reactance is nil.
b. Capacitive reactance is nil.
c. The impedance is nil.
d.* The capacitive and inductive reactance are equal.
62 The parallel tuned circuit impedance at resonance is:
a. Low.
b.* High.
c. Infinitely high.
d. Equal to 10.
63 The series tuned circuit impedance at resonance is:
a.* Low.
b. High.
c. Infinitely high.
d. Equal to 10.
64 The Q of a resonant circuit determines the:
a. Losses of the circuit.
b. Value of the capacitance required for resonance.
c. The inductor value required for resonance.
d.* Value of increased current through the coil and
capacitor at resonance.
65 The selectivity of a resonant circuit is greater if the
Q factor:
a. Is low.
b. Decreases to 1.
c.* Is high.
d. Remains low.
66 The bandwidth of a resonant circuit is defined by:
a.* The -3db half-power points.
b. The -60db values.
c. The peak values.
d. The RMS values.
67 The principle of operation of a transformer is based
upon:
a. Static electricity.
b. Potential difference.
c. Electrostatics.
d.* Electromagnetic induction.
68 Transformers transfer energy from one coil to another
by means of:
a.* Inductive coupling.
b. Static discharge.
c. Capacitance.
d. Electrical conduction.
69 A transformer with a turns ratio of 1:8 is called:
a. a step down transformer.
b.* a step up transformer.
c. low current transformer.
d. a high tension transformer.
a. 3 V.
b.* 48 V.
c. 16 V.
d. 8 V.
71 On which electrical principle is the functioning of a
transformer based?
a. Stray capacitance.
b.* Mutual inductance.
c. Eddy currents.
d. Circuit resistance.
72 What is the turns ratio of a transformer to match an
audio amplifier having an output impedance of 200 ohms to
a speaker having a load impedance of 10 ohms?
a.* 4.47 to 1.
b. 14.14 to 1.
c. 20 to 1.
d. 400 to 1.
73 The operating principle of a transformer may be
described as:
a.* A varying magnetic field intersecting a conductor and
creating a potential difference.
b. A varying electric field intersecting a conductor and
creating a potential difference.
c. A varying current in a conductor setting up a static
magnetic field.
d. A varying voltage in a conductor setting up a static
magnetic field.
74 In some power transformers a copper sheet is located
between the primary and secondary windings. This sheet is
normally earthed and acts as a:
a. Shield reducing the mutual inductance between primary
and secondary windings.
b.* A shield reducing capacitive coupling between primary
and secondary windings.
c. A shield reducing the hum transfer between primary and
secondary windings.
d. Heat sink.
75 An impedance-matching transformer has a turns ratio of
10:1. If a 500 ohm microphone is connected to the winding
with the lesser turns, it would correctly operate into a
load of:
a. 5 ohm.
b. 50 ohm.
c.* 50 K ohm.
d. 500 K ohm.
76 A transformer has 1200 turns on its primary and 30
turns on its secondary. If it is connected to the mains
supply(240v), the secondary voltage will be:
a. 9600 volt.
b. 240 volt.
c. 30 volt
d.* 6 volt.
77 A transmitter has a power output of 100W. This is
connected to an antenna with 11dB gain by means of a coax
cable with a loss of 1dB. The ERP of the antenna is:
a. 11w.
b. 111w.
c.* 1000w.
d. 2000w.
78 An increase in power from 0,25 watt to 1,25 watt is
equal to a gain of:
a. 3 dB.
b.* 7 dB.
c. 10 dB.
d. 1 dB.
79 An -20 dB attenuator is placed in line with a 40V RMS
signal. Assuming the impedances all remain constant what
will the reduced signal level be?
a. 2 Volt.
b. 10 Volt.
c. 20 Volt.
d.* 4 Volt.
80 A power gain of 4 is equivalent to:
a. 3 dB.
b.* 6 dB.
c. 10 dB.
d. 16 dB.
81 The term heterodyne is used to describe:
a.* The mixing of two signals.
b. The temperature of a device.
c. The condition when the voltage is in phase with the
current.
d. The condition of resonance.
82 A signal of 1 kHz and one of 30 kHz are applied to a
mixer. What outputs will be obtained before filtering?
a. 1kHz and 30 kHz only.
b. 29 kHz and 31 kHz only.
c. 31 kHz only.
d.* 1 kHz, 29 kHz, 30 kHz and 31 kHz.
83 The antenna connected to a super heterodyne receiver
applies a signal of 3500 kHz to the mixer stage. If the IF
frequency is 455 kHz, which of the following will be the
local oscillator frequency?
a. 2645 kHz.
b.* 3955 kHz.
c. 945 kHz.
d. 545 kHz.
84 The tolerance of a resistor is indicated as 10 %. If
the nominal value is 4700 ohm then the value must lie
between:
a. 4230 and 5170 ohm.
b.* 4653 and 4747 ohm.
c. 4230 and 4747 ohm.
d. 4653 and 5170 ohm.
85 To prevent stray fields effecting nearby circuits,
inductors should best be screened with:
a. Glass.
b.* Copper.
c. Paper.
d. Air.
86 What is the function of screening?
a. To hide components from view.
b. To remove heat from a component.
c.* To prevent feedback of signals from an output to a
sensitive input.
d. To increase circuit efficiency.
87 To prevent an unwanted strong signal from getting to
the input of a sensitive amplifier one can:
a.* Screen the amplifier input stage.
b. Decrease the volume setting.
c. Reduce the supply voltage.
d. Increase the amplifier impedance.
88 Crystals used for radio circuits are cut from a
material called:
a. Glass.
b. Resin.
c. Plastic.
d.* Quartz.
89 The frequency of a crystal can be pulled by:
a. Applying a higher voltage.
b.* Connecting a parallel capacitor.
c. Re-orientating the crystal.
d. Using a crystal calibrator.
90 The quartz crystal is equivalent to:
a. a low pass filter.
b. a high pass filter.
c.* a high Q tuned circuit.
d. a rectifier.
91 Which of the following circuits or components rely for
its operation on the piezoelectric effect?
a. Carbon microphone.
b. Balanced modulator.
c.* Marker oscillator.
d. Solid state rectifier.
92 The area of a diode junction where no free holes or
electrons exist is called the:
a. Anode.
b. Cathode.
c.* Depletion region.
d. Semiconductor.
93 The forward biased diode junction will:
a.* Allow current to flow through the junction.
b. Block current from flowing.
c. Have a high resistance.
d. Exhibit a zener diode function.
94 In a silicon diode the voltage of 0,6 Volt refers to:
a. The breakdown voltage.
b.* The forward bias voltage.
c. The zener voltage.
d. The cut-off voltage.
95 What is the required peak-inverse-voltage rating of a
power supply rectifier?
a. The highest transient voltage the diode will handle.
b. 1,4 times the ac voltage.
c.* The maximum voltage that can be applied in the reverse
biased direction.
d. 2,8 times the ac voltage.
96 Which of the following components is intended only to
operate in the reverse biased condition?
a. A rectifier diode.
b.* A zener diode.
c. A polarized capacitor.
d. A resistor.
97 The term Vz is commonly used to describe:
a.* The zener diode regulating voltage.
b. The zener diode impedance.
c. The forward voltage applied to the diode.
d. The peak voltage of the rectified waveform.
98 An PN type semiconductor refers to a :
a. Two pin transistor.
b. A capacitor.
c.* A diode.
d. A power resistor.
'n PN-tipe halfgeleier verwys na ‘n:
99 By only allowing Alternating current to flow in one
direction a diode can be used as:
a. An attenuator.
b. An amplifier.
c.* A rectifier.
d. A fuse.
100 Zener diodes are used to:
a. Start oscillations.
b. Divert signals.
c. Detect modulation.
d.* Regulate a DC voltage supply.
101 To vary the capacitance in a tuned circuit with
voltage, use is made of a:
a.* Varicap diode.
b. Tuning tool.
c. Resistor divider.
d. Zener diode.
102 The varicap diode uses the width of the depletion
layer to:
a. Vary the reverse bias current.
b.* Vary its capacitance.
c. Vary its frequency.
d. Vary its resistance.
103 A type of diode useful for mixer or detector circuits
well into the microwave region is:
a.* Hot-carrier diode.
b. Zener diode.
c. Triac.
d. Avalanche Rectifier diode.
104 Light emitting diodes are commonly used in:
a. Detector circuits of TRF receivers.
b. Diode ring modulators.
c. Diode product detectors.
d.* Logic driven visual read-outs.
105 Diodes can be used in:
a. Power supply rectifiers.
b. Signal detectors.
c. Field strength meters.
d.* All of the above.
106 Which of the following components rectify AC to DC?
a. Capacitors.
b.* Diodes.
c. Resistors.
d. Transformers.
107 Which of the following are semiconductors?
a. NPN Transistors.
b. PNP Transistors.
c. Rectifier diodes.
d.* All of the above.
108 What function does a full-wave bridge circuit serve?
a. Amplification.
b. Coupling.
c.* Rectification.
d. Isolation.
109 The terms Schottky, IMPATT, LED and Gun are used to
describe:
a.* Diodes.
b. Power sources.
c. Capacitors.
d. Oscillators.
110 If the base potential of a NPN transistor is held at
the emitter potential, the collector current will be
a.* Zero.
b. Always 1 Amp.
c. Between 10 mA and 2A.
d. Very high.
111 The output impedance of an emitter follower buffer
amplifier is
a. Infinite.
b. Very high.
c. 0.
d.* Fairly low.
112 For a silicon transistor to conduct:
a.* The base-emitter must be forward biased by 0,6V.
b. The base must be connected to the emitter.
c. The collector must be connected to the emitter.
d. The base lead must be disconnected.
113 In a transistor amplifier circuit where full base
current always flows, the circuit is biased for:
a.* Class A amplifier.
b. Class B amplifier.
c. Class AB amplifier.
d. Class C Amplifier.
114 A class C amplifier conducts over
a. The complete cycle.
b. Three quarters of the cycle.
c. Exactly half a cycle.
d.* Less than half a cycle.
115 The amplifier class which has the lowest distortion
figures is:
a.* Class A.
b. Class B.
c. Class AB.
d. Class C.
116 An amplifier that operates under conditions of bias
and supply such that conduction occurs for more than 180
degrees but less than 360 degrees of a complete input
cycle is operating in class:
a. Class A.
b.* Class AB.
c. Class B.
d. Class C.
117 Which of the following would not use a Class C
amplifier?
a. An oscillator.
b. FM power amplifier.
c. CW power amplifier.
d.* An audio speech amplifier.
118 When an RF power amplifier is biased for a conduction
angle of more than 360 degrees:
a. Output current flows for only part of the input cycle.
b.* Bias current never shuts off the device.
c. The average grid voltage is twice cutoff voltage.
d. RF power is produced at greatest efficiency.
119 The three terminals of a FET are:
a. Gate, Source and Emitter.
b.* Gate, Source and Drain.
c. Gate, Emitter and Collector.
d. Base, Source and Drain.
120 Another name for positive feedback is:
a.* Regeneration.
b. Decoupling.
c. Rectification.
d. Phase shift.
121 The names Clapp, Colpitts, Hartley refer to:
a. Transistors.
b. Power amplifiers.
c.* Oscillators.
d. Diodes.
122 Which of the following is NOT a basic requisite for
oscillation?
a. Feedback from output to input of the amplifier.
b. Correct phasing of input and output circuits.
c. Amplifying of signals from input to output.
d.* Tuned circuit in both input and output stages.
123 The purpose of an amplifier in an oscillator is to:
a. Cancel phase shift.
b.* Compensate for circuit losses.
c. Produce an increasing output.
d. Act as an oscillator buffer.
124 An oscillator varies its frequency as the loading on
the following power amplifier is increased. In redesigning
this circuit use should be made of:
a. A more powerful oscillator.
b. A well-regulated DC supply.
c. * An intermediate buffer stage.
d. Decreased L/C ratio in the oscillator.
125 A frequency multiplier stage is generally:
a.* Biased into non-linearity.
b. Operated in class A.
c. Used with regeneration.
d. Used in processing SSB signals.
126 Colpitts, Clapp, Gouriet, Beat Frequency and Crystal
are all types of :
a. Tuners.
b.* Oscillators.
c. Antennas.
d. Amplifiers.
127 The characteristic of an oscillator which determines
its operating frequency is:
a. Its resistance.
b.* Its resonant frequency.
c. Its inductive reactance.
d. Its size.
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