Sample Exam 4

Fundamentals of Electricity & Radio Communications sample paper-4

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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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Congratulations - you have completed Fundamentals of Electricity & Radio Communications sample paper-4. You scored %%SCORE%% out of %%TOTAL%%. Your performance has been rated as %%RATING%%

Your answers are highlighted below.

Question 1

The conductivity of a current carrying conductor can be decreased by

A	reducing its temperature
B	reducing its length
C	reducing its diameter
D	increasing its diameter

Question 2

The resonance frequency of a tuned (LRC) series circuit is given by

A	1 / [2π√(LC)]
B	(1 / 2π)√(L/C)
C	1 / 2π√(LC)
D	2π/√(LC)

Question 2 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 3

The value of the resistor shown in the figure is

A	210Ω
B	120Ω
C	12Ω
D	21Ω

Question 4

The ability of a receiver to pickup weak signal is

A	sensitivity
B	none of these
C	selectivity
D	stability

Question 5

The automatic gain control (AGC) circuit is usually used to control the gain of the

A	detector
B	IF amplifier
C	mixer
D	audio amplifier

Question 6

An R.F. choke

A	Aids the flow of R.F. current
B	prevent AC ripple.
C	prevent the flow of R.F. current
D	accelerates the flow of R.F.

Question 7

Over modulation in an F.M. transmission will cause

A	to occupy wide bandwidth
B	To occupy narrow bandwidth
C	none of the above
D	Heavy distortion

Question 8

The basic concept of Amplitude Modulation (AM) is to vary the

A	frequency of modulating signal
B	amplitude of modulating signal
C	amplitude of carrier signal
D	frequency of carrier signal

Question 9

The power input of a transistor is

A	collector current X collector voltage
B	base current X collector voltage
C	collector current X emitter current
D	Emitter current x base current

Question 10

What is the effective capacitance between the points A and B shown in the diagram ?

A	18 pF
B	1 pF
C	9pF
D	27 pF

Question 11

A moving coil meter responds only by itself to

A	DC
B	AC+DC
C	Frequency
D	AC

Question 12

A 300 Ohm twin feeder line is

A	an unbalanced line
B	a balanced line
C	none of the above
D	a wave guide

Question 13

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	3.33 W
B	10 W
C	5 W
D	6.67 W

Question 14

A transformer is laminated to

A	increase magnetic flux
B	reduce hysteresis losses
C	reduce eddy current losses
D	increase exciting current

Question 15

The Radiation Resistance of a ½-wave dipole is

A	75 Ohms
B	100 Ohms
C	50 Ohms
D	300 Ohms

Question 16

A fuse is used in an electrical circuit

A	to protect from lightning
B	to prevent AC hum
C	none of these
D	to prevent damage of all equipment due to overload

Question 17

A coaxial cable is

A	an unbalanced line
B	none of these
C	a balanced line
D	a wave guide

Question 18

A dipole is used on 7 MHz will work very efficiently on

A	28 MHz
B	14 MHz
C	3.5 MHz
D	21 MHz

Question 19

A 10 Ohm resistor consumes a current of 1 Ampere. The power dissipated in the resistor is

A	100 Watts
B	1 Watt
C	10 Watts
D	0.1 Watt

Question 20

Radio waves above 30 kHz are called

A	radio frequencies.
B	super high frequencies
C	very high frequencies.
D	Audio frequencies.

Question 21

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 22

The equivalent resistance of the circuit given is

A	11 kΩ
B	10 kΩ
C	1 kΩ
D	22 kΩ

Question 23

A vertical polarized transmission could have for best reception

A	a cross polarized antenna
B	A horizontal receiving antenna
C	a circular polarized antenna
D	a vertical receiving antenna

Question 24

The deviation of a standard 2 meter Amateur Radio Transmitter is

A	2.5 kHz
B	50 kHz
C	5kHz
D	25 kHz

Question 25

If a person gets an electric shock you should immediately

A	Remove the victim to a safe place
B	Switch off the mains supply immediately
C	Give him artificial respiration
D	Send for a doctor

Question 26

The transformer is used to change the value of

A	frequency
B	voltage
C	power
D	none of these

Question 27

Envelope of diode detector is used for the detection of

A	FM signals
B	CW signals
C	AM signals
D	SSB signals

Question 28

What is the total inductance between A and B ?

A	27 mH
B	18 mH
C	1 mH
D	9 mH

Question 29

29.1MHz is the third harmonic of

A	9.7 MHz
B	87.3 MHz
C	19.4 MHz
D	90 MHz

Question 30

One way communication is called

A	monocom
B	simplex
C	duplex
D	half duplex

Question 31

The electric field of an antenna is parallel to the Earth’s surface. The polarization of the antenna is

A	none of these
B	horizontal
C	circular
D	vertical

Question 32

An antenna whose input impedance is 50Ω Should have a feeder link with an impedance of

A	100 Ω
B	75 Ω
C	300 Ω
D	50 Ω

Question 33

To determine the voltage polarity across a resistor, we should know

A	the battery voltage
B	the direction of the current
C	the magnitude of the current
D	the value of the resistor

Question 34

20 dB power gain is an increase power by

A	100 times
B	20 times
C	10 times
D	2 times

Question 35

Which one is incorrect from following statments

A	Power factor of a pure inductor is zero
B	Power factor = actual power / apperent power
C	Power factor of a pure resistor is 1
D	Power factor of a capacitor is infinity

Question 36

The purpose of adding reflector and directors to a folded dipole antenna is

A	none of these
B	to have some effect on its impedance
C	to increase its impedance
D	to decrease its impedance

Question 37

The unit of electric current is

A	Volt
B	Ampere
C	Hertz
D	Ampere hour

Question 38

A sunspot cycle is

A	21 years
B	11 years
C	10 years
D	5 years

Question 39

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 40

The Meggar is used for

A	measuring voltage
B	measuring current
C	measuring power
D	testing insulation

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