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PET 7 Flashcards

1
Q

If the △H of a reaction is a negative
quantity, the reaction is definitely

A. Reversible
B. Endothermic
C. Exothermic
D. Unstable

A

C. Exothermic

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2
Q

Heat transfer by convection occurs

A. only in liquids
B. in gases, liquids and solids
C. only in gases
D. only in gases and liquids

A

D. only in gases and liquids

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3
Q

Which of the following equation of state
has two constants?

A. Strobridge Equation
B. Benedict-Webb-Rubin Equation
C. Beattie-Bridgeman Equation
D. Vander Waals Equation

A

D. Vander Waals Equation

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4
Q

How many constants are there in
Benedict-Webb-Rubin Equation

A. 14
B. 8
C. 16
D. 13

A

B. 8

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5
Q

In order to emit electromagnetic radiation, an object must be at a temperature

A. above 0°C
B. above 0 K
C. high enough for it to glow
D. above that of its surroundings

A

B. above 0 K

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6
Q

The rate at which an object radiates
electromagnetic energy does not
depend on its

A. ability to absorb radiation
B. temperature
C. mass
D. surface area

A

C. mass

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7
Q

It is the transfer of energy from the
more energetic particles of substance
to the adjacent less energetic ones as a
result of interactions between the
particles

A. absorption
B. radiation
C. conduction
D. convection

A

C. conduction

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8
Q

Which of the following is considered the
best conductor of heat?

A. Copper
B. Silver
C. Gold
D. Diamond

A

D. Diamond

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9
Q

It is the mode of energy transfer
between a solid surface and the
adjacent liquid or gas that is in motion,
and it involves the combined effect
conduction and fluid motion

A. conduction
B. radiation
C. absorption
D. convection

A

D. convection

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10
Q

A cycle consisting of one constant
pressure, one constant volume and two
isentropic processes is known as

A. Stirling cycle
B. Otto cycle
C. Diesel cycle
D. Carnot cycle

A

C. Diesel cycle

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11
Q

A cycle consisting of one constant
pressure, one constant volume and two
isentropic processes is known as

A. Otto cycle
B. Stirling cycle
C. Carnot cycle
D. Diesel cycle

A

D. Diesel cycle

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12
Q

If the value of n = 0 in the equation pv =
C, then the process is called

A. constant pressure process
B. constant volume process
C. adiabatic process
D. isothermal process

A

A. constant pressure process

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13
Q

The density of seawater is greater than
that of fresh water. A boat will float:

A. At the same level in both
B. Lower in fresh water than in seawater
C. Higher in fresh water than in seawater
D. Any of these choices, depending upon its
shape

A

B. Lower in fresh water than in seawater

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14
Q

It indicates that the rate of heat
conduction in a direction is proportional
to the temperature gradient in that
direction.

A. Fourier’s Law of Heat Convection
B. Fourier’s Law of Heat Conduction
C. Fourier’s Law of Heat Absorption
D. Fourier’s Law of Heat Radiation

A

B. Fourier’s Law of Heat Conduction

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15
Q

It is the energy emitted by the matter in the form of electromagnetic waves as a result of the changes in the electronic
configurations of the atom or
molecules.

A. Radiation
B. Convection
C. Absorption
D. Conduction

A

A. Radiation

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16
Q

It states that energy can neither be destroyed nor created; it can only change forms.

A. First law of thermodynamics
B. Second law of thermodynamics
C. Third law of thermodynamics
D. Zeroth law of thermodynamics

A

A. First law of thermodynamics

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17
Q

In second law of thermodynamic, which of the following state that no device can transfer heat from cooler body to a
warmer one without leaving an effect on
the surroundings.

A. Clausius Statement
B. Clausius-Plank Statement
C. Kelvin Statement
D. Kelvin -Plank Statement

A

A. Clausius Statement

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18
Q

It is defined as the amount of light
output in lumens per W of electricity
consumed.

A. Light efficacy
B. Light intensity
C. Light luminosity
D. Light efficiency

A

A. Light efficacy

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19
Q

Carnot cycle is composed of how many
reversible processes?

A. 2
B. 1
C. 3
D. 4

A

D. 4

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20
Q

Which of the following processes are
involved in Carnot cycle?

A. Three isobaric; one adiabatic
B. Two adiabatic; two isothermal
C. One isothermal; three adiabatic
D. Two isothermal; two isobaric

A

B. Two adiabatic; two isothermal

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21
Q

State that the thermal efficiencies of all
reversible heat engines operating
between the same two reservoirs are the same, and that no heat engine is more efficient than a reversible one operating between the same two
reservoirs.

A. Otto principle
B. Kelvin principle
C. Carnot principle
D. Throttle principle

A

C. Carnot principle

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22
Q

It states that if two bodies are in
thermal equilibrium with a third body,
they are also in thermal equilibrium with
each other

A. Zeroth law of thermodynamics
B. Third law of thermodynamics
C. Second law of thermodynamics
D. First law of thermodynamics

A

C. Second law of thermodynamics

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23
Q

It explains combustion as a result of
loss of a substance.

A. Roasting
B. Phlogiston
C. Fission
D. Reduction

A

B. Phlogiston

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24
Q

The volume of a definite quantity of dry
gas is inversely proportional to the
pressure provided the temperature
remains constant.

A. Boyle’s Law
B. Dalton’s Law
C. Gay-Lussac’s Law
D. Charles’ Law

A

A. Boyle’s Law

25
Q

It is the enthalpy change associated
with the condensation of gaseous
positive and negative ion into a crystal.

A. Raoult’s Law
B. Enthalpy of Solution
C. Lattice Energy
D. Partition Coefficient

A

C. Lattice Energy

26
Q

This Law states that if a process can be written as the sum of several stepwise processes, the Enthalpy change the
total process equals the sum of the
Enthalpy changes of the Various Steps.

A. Hess Law
B. Newton’s Law
C. Gauss Law
D. Boyles Law

A

A. Hess Law

27
Q

_____ states that a constant
pressure and temperature, the volume of a gas is directly proportional to the number of moles present.

A. Gay-Lussac’s Law
B. Boyle’s Law
C. Avogrado’s Law
D. Charle’s Law

A

C. Avogrado’s Law

28
Q

states that the partial pressure of a solvent over a solution is given by the vapor pressure of the pure solventbtimes the mole fraction of the solvent in the solution.

A. Raoult’s Law
B. Dalton’s Law of partial pressure
C. de Broglie’s hypothesis
D. Aufbau principle

A

A. Raoult’s Law

29
Q

The property of a substance which
remains constant if no heat enters or
leaves the system, while it does work or alters its volume, but which increases or diminishes should a small amount of
heat enter or leave.

A. Enthalpy
B. entropy
C. system
D. Internal energy

A

B. entropy

30
Q

The property of a substance which
remains constant if no heat enters or
leaves the system, while it does work or alters its volume, but which increases or diminishes should a small amount of
heat enter or leave.

A. Enthalpy
B. entropy
C. system
D. Internal energy

A

B. entropy

31
Q

The quantity of heat required to change
the temperature of unit mass through
one degree.

A. Specific Heat
B. Calorie
C. Thermal Equilibrium
D. Temperature

A

A. Specific Heat

32
Q

The energy stored in a substance by
virtue of the activity and configuration of its molecules and of the vibration of the atoms within the molecules.

A. Heat
B. Enthalpy
C. Entropy
D. Internal Energy

A

D. Internal Energy

33
Q

Waveguide-Derived Components are that components made from sections of a waveguide. These components
perform various special functions depending on the construction and preparations. Among these
components, what is the name of the waveguide section used to change the signal polarization?

A. Twist
B. Bend
C. Tee
D. Resonator

A

A. Twist

34
Q

Which of the following choices below is
the primary purpose of a dummy load?

A. To prevent over-modulation of your
transmitter
B. To improve the radiation from your
antenna
C. To improve the signal to noise ratio of your
receiver
D. To prevent the radiation of signals
when making tests

A

D. To prevent the radiation of signals
when making tests

35
Q

The type of wave that is limited to line-
of-sight transmission distances is:

A. all of these choices
B. ground wave.
C. space wave.
D. sky wave.

A

C. space wave.

36
Q

Microwave Communication System is
communication system utilizing
microwave frequencies to transmit
information from one place to another.
Also, this type of communication
system uses waveguide to transmit
signals instead of ordinary transmission
lines. What do you call the range of
microwave frequencies more easily passed by the atmosphere than the others in this type of communication system?

A. resonance in the atmosphere
B. critical frequency
C. gyro frequency range
D. window

A

D. window

37
Q

Radio propagation is the behavior of
radio waves when they are transmitted by an antenna, or propagated from one point on the Earth to another, or into
various parts of the atmosphere. As a form of electromagnetic radiation, like light waves, radio waves after
transmitted by an antenna are affected
by the phenomena of reflection,
refraction, diffraction, absorption,
polarization, and scattering. If the
electric field is propagating parallel to
the surface of the earth, the polarization
is said to be _____

A. Circular
B. Vertical
C. Elliptical
D. Horizontal

A

D. Horizontal

38
Q

In the field of antenna design the term
radiation pattern refers to the directional(angular) dependence of the strength of the radio waves from the antenna or
other source. In a certain antenna
transmitting a Very High Frequency
electromagnetic wave in a direction 30
degrees south of the west, the region
within the influence of the induction
field of an antenna is called what?

A. Near field
B. Far field
C. Radiation pattern
D. Radiation field

A

A. Near field

39
Q

In radio communication, “skywave”or
“skip” refers to the propagation of radio
waves reflected or refracted back
toward Earth from the ionosphere, an electrically charged layer of the upper atmosphere. Since it is not limited by the curvature of the Earth, skywave
propagation can be used to
communicate beyond the horizon, at
intercontinental distances. It is mostly
used in the shortwave frequency bands.In sky wave propagation terminologies,what is the term for the area that lies
between the outer limit of the ground
wave range and the inner edge of
energy return from the ionosphere?

A. duct zone
B. skip zone
C. Optical horizon
D. skip distance

A

B. skip zone

40
Q

When microwave signals transmitted
from a high power transmitting antenna
from a certain country in a continent
near the equator follow the curvature of
the earth, this is known as:

A. tropospheric scatter
B. the Faraday effect
C. ionospheric reflection
D. ducting

A

D. ducting

41
Q

What term describes a wide-bandwidth
communications system in which the
RF carrier varies according to some pre-
determined sequence?

A. Frequency Modulation
B. Time-domain frequency modulation.
C. FSK
D. Spread-spectrum communication.

A

D. Spread-spectrum communication.

42
Q

In telecommunications, a diversity
scheme refers to a method for
improving the reliability of a message
signal by using two or more
communication channels with different characteristics. Diversity is mainly used in radio communication and is a
common technique for combatting
fading and co-channel interference and avoiding error bursts. It is based on the fact that individual channels experience different levels of fading and
interference. Multiple versions of the
same signal may be transmitted and/or
received and combined in the receiver
There are different classes of diversity schemes depending on how it is done.From these different classes, space
diversity transmission means
transmitting and receiving on

A. two or more antennas operating on two
different frequencies
B. two or more identical frequency
C. two or more different frequency
D. two or more antennas operating on the
same frequency

A

D. two or more antennas operating on the
same frequency

43
Q

At distances greater than the skip
distance in a sky wave propagation or
ionospheric propagation sometimes,
since it uses the ionosphere to send the
signal from the transmitting station
back to the earth to the receiving
station, two rays can take different
paths and still be returned to the same
point on earth. These two rays are
called lower ray and _____

A. Huygen’s ray
B. Pedersen ray
C. Heaviside ray
D. Miller’s ray

A

B. Pedersen ray

44
Q

Ground Wave propagation is a method
of radio frequency propagation that
uses the area between the surface of
the earth and the ionosphere for
transmission. The ground wave can
propagate a considerable distance over
the earth’s surface particularly in the
low frequency and medium frequency portion of the radio spectrum. Ground wave radio propagation is used to
provide relatively local radio
communications coverage. Ground
wave radio signal propagation is ideal
for relatively short distance propagation
on these frequencies during the
daytime. In this type of radio wave
propagation, the ground wave signals eventually disappears, as moves away from the transmitter, because of

A. loss of line-of-sight conditions
B. tilting
C. interference from the sky wave
D. maximum single hop distance limitations

A

B. tilting

45
Q

A microwave signal to be carried by a
waveguide is introduced into one end of
the waveguide that creates an
electromagnetic wave that propagates through the waveguide. The electric and magnetic fields associated with the
signal bounce off the inside walls back and forth as the signal progresses down the waveguide. The waveguide totally
contains the signal so that none
escapes by radiation. A coupling loop is
placed at a point of

A. maximum magnetic and electric field
intensity
B. maximum electric field intensity
C. most convenient place
D. maximum magnetic field intensity

A

D. maximum magnetic field intensity

46
Q

Among the frequency bands for this radio waves, which of the following is also known as millimetric waves

A. UHF
B. VLF
C. MF
D. EHF

A

D. EHF

47
Q

With regard to satellite
communications, what is Doppler shift?

A. A mode where the satellite receives
signals on one band and transmits on
another
B. An observed change in signal
frequency caused by relative motion between the satellite and the earth station
C. A special digital communications mode for
some satellites
D. A change in the satellite orbit

A

B. An observed change in signal
frequency caused by relative motion between the satellite and the earth station

48
Q

The TWT is sometimes preferred to the
multicavity klystron amplifier, because it

A. is more efficient
B. has a greater bandwidth
C. has a higher number of modes
D. produces a higher output power

A

B. has a greater bandwidth

49
Q

Due to reciprocity, the gain of any
antenna when receiving is equal to its gain when transmitting. What is meant by the gain of an antenna?

A. The additional power that is lost in the antenna when transmitting on a higher frequency
B. The additional power that is added to the
transmitter power
C. The increase in signal strength in a
specified direction when compared to a
reference antenna
D. The increase in impedance on receive or
transmit compared to a reference antenna

A

C. The increase in signal strength in a
specified direction when compared to a
reference antenna

50
Q

A klystron is a microwave vacuum tube
using cavity resonators to produce
velocity modulation of the electron
beam and produce amplification while a
magnetron is a crossed-field device
combination of a simple diode vacuum tube with built-in cavity resonator and an extremely powerful permanent
magnet. Both devices are used to
generate microwave frequencies in the
cm to mm wavelength region. The
operating frequency of these klystrons
and magnetrons are set by the

A. Cavity resonators
B. DC supply voltage
C. Number of cavi
D. Input signal frequency

A

A. Cavity resonators

51
Q

At low frequencies (below about 300
MHz), the characteristics of open and
shorted lines have little significance. At
low frequencies the lines are just too
long to be used as reactive components or as filters and tuned circuits. However,at UHF (300 to 3000 MHz) and
microwave (1 GHz and greater)
frequencies the length of one-half
wavelength is less than 1 ft; the values of inductance and capacitance become so small that it is difficult to realize
them physically with standard coils and capacitors. Special transmission lines constructed with copper patterns on a printed circuit board (PCB), called
microstrip or stripline, can be used as
tuned circuits, filters, phase shifters,
reactive components, and impedance-
matching circuits at these high
frequencies. A disadvantage of
microstrip with respect to stripline
circuits is that the former

A. is more likely to radiate
B. is bulkier
C. is more expensive and complex to
manufacture
D. do not lend itself to printed circuit
techniques

A

A. is more likely to radiate

52
Q

The term for the case when the same signal arrives at the TV receiver at the two different times is:

A. pulsing
B. ghosting
C. tagging
D. phasing

A

B. ghosting

53
Q

A term used to describe variations in
signal strength that occur at a receiver
during the time a signal is being
received is known as:

A. refraction.
B. fading.
C. skipping.
D. bouncing.

A

B. fading.

54
Q

One wavelength of waveguide, when compared to one wavelength of free space is:

A. all of these choices
B. larger.
C. the same length.
D. smaller.

A

B. larger.

55
Q

Between the point where the ground
wave is completely dissipated and the point where the fist sky wave returns is called _____

A. quiet zone
B. fading
C. skip zone
D. quiet zone and skip zone

A

D. quiet zone and skip zone

56
Q

An antenna array is a set of individual antennas used for transmitting and/or receiving radio waves, connected
together in such a way that their
individual currents are in a specified
amplitude and phase relationship. This
allows the array to act as a single
antenna, generally with improved
directional characteristics (thus higher antenna gain) than would be obtained from the individual elements. In a
parasitic array,

A. Only one of the elements is driven, the
others get excitation from the field
produced by the driven element
B. both Only one of the elements is driven, the
others get excitation from the field
produced by the driven element and All the
elements in the antenna get excitation
from inductive coupling.
C. Only one of the elements is driven, the
others get excitation from the field taken
from the transmission line
D. All the elements in the antenna get
excitation from inductive coupling.

A

A. Only one of the elements is driven, the
others get excitation from the field
produced by the driven element

57
Q

A waveguide is a structure that guides waves, such as electromagnetic waves or sound waves. They enable a signal to propagate with minimal loss of energy by restricting expansion to one-
dimension, or two. This is a similar
effect to waves of water constrained
within a canal, or why guns have barrels
that restrict hot gas expansion to
maximize energy transfer to their
bullets. Without the physical constraint
of a waveguide, signals will typically
dissipate according to the inverse
square law as they expand into three
dimensional space. There are different types of waveguides for each type of wave. The original and most common meaning is a hollow conductive metal pipe used to carry high frequency radio waves, particularly microwaves
Waveguides are used mainly for
microwave signals because

A. they depend on straight-line propagation
which applies to microwaves only
B. losses would be too heavy at lower
frequencies
C. they would be too bulky at lower
frequencies
D. there are no generators powerful enough
to excite them at lower frequencies

A

C. they would be too bulky at lower
frequencies

58
Q

An optical coupler found in a link
connecting Telco A and Telco B has
several input ports and several output ports. Which of the following types of optical couplers is it?

A. Star Coupler
B. Optical Combiner
C. Tree Coupler
D. Optical Splitter

A

A. Star Coupler

PET (3 decks)

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