Fundamentals of Electricity & Radio Communications sample paper-4
By
The Radio Society of Sri Lanka
The copy right of the information contained in this sample exam are with the Radio Society of Sri Lanka (RSSL).
These questions are mainly targeting the Radio Amateur exam for Novice and General class. The recommended time duration is 1 hour. For more information please contact Mr. Jayasiri Wijeratne (4S7VJ) 4s7vj@rssl.lk
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Question 1 |
The deviation of a standard 2 meter Amateur Radio Transmitter is
A | 2.5 kHz |
B | 5kHz |
C | 50 kHz |
D | 25 kHz |
Question 2 |
One way communication is called
A | duplex |
B | half duplex |
C | monocom |
D | simplex |
Question 3 |
The unit of electric current is
A | Hertz |
B | Ampere |
C | Volt |
D | Ampere hour |
Question 4 |
A | 9pF |
B | 27 pF |
C | 1 pF |
D | 18 pF |
Question 5 |
The value of the resistor shown in the figure is

A | 12Ω |
B | 120Ω |
C | 21Ω |
D | 210Ω |
Question 6 |
How can key clicks be eliminated?
A | Should have a regulated power supply |
B | Have an antenna matching device. |
C | Neutralize the P.A. |
D | Use a key click filter |
Question 7 |
A coaxial cable is
A | a wave guide |
B | a balanced line |
C | an unbalanced line |
D | none of these |
Question 8 |
The electric field of an antenna is parallel to the Earth’s surface. The polarization of the antenna is
A | vertical |
B | none of these |
C | circular |
D | horizontal |
Question 9 |
A | 11 kΩ |
B | 10 kΩ |
C | 22 kΩ |
D | 1 kΩ |
Question 10 |
20 dB power gain is an increase power by
A | 100 times |
B | 2 times |
C | 20 times |
D | 10 times |
Question 11 |
A dipole is used on 7 MHz will work very efficiently on
A | 21 MHz |
B | 28 MHz |
C | 14 MHz |
D | 3.5 MHz |
Question 12 |
Which one is incorrect from following statments
A | Power factor of a pure inductor is zero |
B | Power factor of a pure resistor is 1 |
C | Power factor of a capacitor is infinity |
D | Power factor = actual power / apperent power |
Question 13 |
The Radiation Resistance of a ½-wave dipole is
A | 300 Ohms |
B | 100 Ohms |
C | 50 Ohms |
D | 75 Ohms |
Question 14 |
The Meggar is used for
A | measuring voltage |
B | measuring power |
C | testing insulation |
D | measuring current |
Question 15 |
Radio waves above 30 kHz are called
A | Audio frequencies. |
B | super high frequencies |
C | very high frequencies. |
D | radio frequencies. |
Question 16 |
A sunspot cycle is
A | 5 years |
B | 11 years |
C | 10 years |
D | 21 years |
Question 17 |
A fuse is used in an electrical circuit
A | none of these |
B | to prevent damage of all equipment due to overload |
C | to protect from lightning |
D | to prevent AC hum |
Question 18 |
The conductivity of a current carrying conductor can be decreased by
A | reducing its diameter |
B | increasing its diameter |
C | reducing its length |
D | reducing its temperature |
Question 19 |
The automatic gain control (AGC) circuit is usually used to control the gain of the
A | audio amplifier |
B | IF amplifier |
C | detector |
D | mixer |
Question 20 |
The power input of a transistor is
A | collector current X emitter current |
B | Emitter current x base current |
C | collector current X collector voltage |
D | base current X collector voltage |
Question 21 |
If a person gets an electric shock you should immediately
A | Give him artificial respiration |
B | Send for a doctor |
C | Switch off the mains supply immediately |
D | Remove the victim to a safe place |
Question 22 |
The ability of a receiver to pickup weak signal is
A | stability |
B | selectivity |
C | sensitivity |
D | none of these |
Question 23 |
What happens to the input impedance of a Yagi antenna when more elements are added ?
A | will cause unbalanced |
B | Decreases |
C | remains unchanged |
D | increases |
Question 24 |
29.1MHz is the third harmonic of
A | 9.7 MHz |
B | 90 MHz |
C | 19.4 MHz |
D | 87.3 MHz |
Question 25 |
The purpose of adding reflector and directors to a folded dipole antenna is
A | none of these |
B | to decrease its impedance |
C | to have some effect on its impedance |
D | to increase its impedance |
Question 26 |
The transformer is used to change the value of
A | frequency |
B | none of these |
C | voltage |
D | power |
Question 27 |
Over modulation in an F.M. transmission will cause
A | Heavy distortion |
B | to occupy wide bandwidth |
C | none of the above |
D | To occupy narrow bandwidth |
Question 28 |
A transformer is laminated to
A | increase exciting current |
B | increase magnetic flux |
C | reduce hysteresis losses |
D | reduce eddy current losses |
Question 29 |
The resonance frequency of a tuned (LRC) series circuit is given by
A | (1 / 2π)√(L/C) |
B | 2π/√(LC) |
C | 1 / [2π√(LC)] |
D | 1 / 2π√(LC) |
Question 29 Explanation:
The correct answer is 1 / [2π√(LC)] ; but 1 / 2π√(LC) is confused whether it is equal to 1 / [2π√(LC)] or [1 / 2] π√(LC)
Question 30 |
An R.F. choke
A | accelerates the flow of R.F. |
B | Aids the flow of R.F. current |
C | prevent the flow of R.F. current |
D | prevent AC ripple. |
Question 31 |
The basic concept of Amplitude Modulation (AM) is to vary the
A | frequency of carrier signal |
B | frequency of modulating signal |
C | amplitude of modulating signal |
D | amplitude of carrier signal |
Question 32 |
To determine the voltage polarity across a resistor, we should know
A | the battery voltage |
B | the value of the resistor |
C | the direction of the current |
D | the magnitude of the current |
Question 33 |
A 10 Ohm resistor consumes a current of 1 Ampere. The power dissipated in the resistor is
A | 1 Watt |
B | 100 Watts |
C | 0.1 Watt |
D | 10 Watts |
Question 34 |
A 300 Ohm twin feeder line is
A | an unbalanced line |
B | a wave guide |
C | a balanced line |
D | none of the above |
Question 35 |
Envelope of diode detector is used for the detection of
A | SSB signals |
B | AM signals |
C | FM signals |
D | CW signals |
Question 36 |
An antenna whose input impedance is 50Ω Should have a feeder link with an impedance of
A | 75 Ω |
B | 50 Ω |
C | 100 Ω |
D | 300 Ω |
Question 37 |
A vertical polarized transmission could have for best reception
A | A horizontal receiving antenna |
B | a cross polarized antenna |
C | a circular polarized antenna |
D | a vertical receiving antenna |
Question 38 |
A moving coil meter responds only by itself to
A | AC |
B | Frequency |
C | DC |
D | AC+DC |
Question 39 |
The total power content of an amplitude modulated signal is 10W, and the percentage modulation is 100%. The power transmitted by the side bands is
A | 5 W |
B | 10 W |
C | 3.33 W |
D | 6.67 W |
Question 40 |
A | 18 mH |
B | 1 mH |
C | 9 mH |
D | 27 mH |
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