PET 7 Flashcards by Dave Molina

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

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

C. Exothermic

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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

D. only in gases and liquids

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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

D. Vander Waals Equation

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

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

B. 8

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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

B. above 0 K

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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

C. mass

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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

C. conduction

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

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

D. Diamond

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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

D. convection

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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

C. Diesel cycle

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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

D. Diesel cycle

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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. constant pressure process

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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

B. Lower in fresh water than in seawater

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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

B. Fourier’s Law of Heat Conduction

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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. Radiation

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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. First law of thermodynamics

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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. Clausius Statement

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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. Light efficacy

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Carnot cycle is composed of how many
reversible processes?

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

D. 4

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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

B. Two adiabatic; two isothermal

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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

C. Carnot principle

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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

C. Second law of thermodynamics

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

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

B. Phlogiston

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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

Study These Flashcards

A. Boyle’s Law

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

C. Lattice Energy

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. Hess Law

_____ 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

C. Avogrado's Law

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. Raoult's Law

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

B. entropy

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. Specific Heat

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

D. Internal Energy

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. Twist

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

D. To prevent the radiation of signals when making tests

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.

C. space wave.

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

D. window

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

D. Horizontal

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. Near field

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

B. skip zone

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

D. ducting

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.

D. Spread-spectrum communication.

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

D. two or more antennas operating on the same frequency

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

B. Pedersen ray

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

B. tilting

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

D. maximum magnetic field intensity

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

D. EHF

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

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

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

B. has a greater bandwidth

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

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

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. Cavity resonators

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. is more likely to radiate

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

B. ghosting

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.

B. fading.

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.

B. larger.

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

D. quiet zone and skip zone

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

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

C. they would be too bulky at lower frequencies

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. Star Coupler

PET 7 Flashcards

(58 cards)