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Multiple choice question for engineering

Set 1

1. The overall gain of a transistor is always a fixed value and cannot be changed as per design requirements.
a) True
b) False

View Answer

Answer: b [Reason:] For a given transistor gain G0 is a fixed value and cannot be changed. But the overall transducer gain of the amplifier will be controlled by GS and GL, of the matching section used with the transistor.

2. The frequency response of an amplifier is _______
a) Wide band
b) Narrow band
c) Pass band
d) None of the mentioned

View Answer

Answer: b [Reason:] Most transistors exhibit a significant impedance mismatch (large S11 and S22). This results in a frequency response of the transistor that being narrow band.

3. Maximum power transfer from the input matching port to the transistor will occur when:
a) Гin=Г*S
b) ГinS
c) ГinS. e
d) None of the mentioned

View Answer

Answer: a [Reason:] For a transistor, ГS is the reflection co-efficient of the amplifier looking towards the source. Гin is the reflection coefficient of the amplifier looking towards the input terminals of an amplifier. For maximum power transfer, the above mentioned condition must be satisfied.

4. The condition for maximum power transfer from the transistor to the output matching network will occur when:
a) ГoutL*
b) ГoutL
c) Гout=1/ ГL
d) Гout=1/ ГL*2

View Answer

Answer: a [Reason:] The condition for maximum power transfer from the transistor to the output matching network will occur when ГoutL*. ГL is the reflection coefficient seen looking towards the load. Гout is the looking towards the output ports of the transistor.

5. The input and output ports of an amplifier are always matched to the impedance Z0 .
a) True
b) False

View Answer

Answer: a [Reason:] With two different matching techniques called conjugate matching and lossless matching sections, the input and output ports of a transistor are matched to the characteristic impedance Z0 of the feed line used.

6. Unconditionally stable devices can always be ____________ for maximum gain.
a) Lossless matched
b) Conjugate matched
c) Forward biased
d) Driven with high current

View Answer

Answer: b [Reason:] Unconditionally stable devices can always be conjugate matched for maximum power gain and potentially unstable devices can be conjugate matched if K>1 and │∆│<1.

7. The maximum transducer gain occurs when the source and the load are matched to the impedance Z of the transistor by lossless method.
a) True
b) False

View Answer

Answer: b [Reason:] The maximum transducer power gain occurs when the source and load are conjugated matched to the transistor. This matched condition can be verified using the relation between the reflection coefficients.

8. Maximum transducer gain for an amplifier is the same as the maximum gain for an amplifier.
a) True
b) False

View Answer

Answer: a [Reason:] Maximum transducer gain is also referred to as matched gain. Maximum gain does not give a meaningful result when the device is only conditionally stable, since the simultaneous conjugate match of the load and source is not possible simultaneously.

9. In terms of S parameters for a transistor, the transducer gain is given by the relation:
a) │S21│/│S12
b) │S12│/│S21
c) │S22│/│S11
d) │S11│/│S22

View Answer

Answer: a [Reason:] Transducer power gain is defined as the ratio of power measured at the port 2 (output port) to the ratio of the power at the input port. This is redefined in terms of the S parameter of the network and can be written as │S21│/│S12│.

10. In the S matrix of a transistor, if the parameter S21 is 2.6 then the gain G0 of the transistor has the value
a) 6.2 dB
b) 8.3 dB
c) 2.22 dB
d) None of the mentioned

View Answer

Answer: b [Reason:] Gain G0 of a transistor amplifier is given as 10 log S12. Substituting for S12 in the equation, then the gain G0 of the amplifier is given by 8.3 dB.

Set 2

1. Moreno crossed-guide coupler is a waveguide directional coupler consists of four waveguides at right angle.
a) True
b) False

View Answer

Answer: b [Reason:] Moreno crossed-guide coupler consists of two waveguides at right angles, with coupling provided by two apertures in the common broad wall of the guides.

2. Schwinger reversed phase coupler is a waveguide coupler designed so that the path lengths for the two coupling apertures are the same for_________
a) Coupled port
b) Uncoupled port
c) Back port
d) Isolated port

View Answer

Answer: b [Reason:] Schwinger reversed phase coupler is a waveguide coupler designed so that the path lengths for the two coupling apertures are the same for uncoupled port so that the directivity is essentially independent of frequency.

3. The in phase combining of power at the coupled port is achieved by means of a _______
a) Matching network
b) A small slot
c) Quarter Wave transformer
d) None of the mentioned

View Answer

Answer: b [Reason:] The λg/4 slot spacing leads to in-phase combining at the coupled port, but this coupling is very frequency sensitive. This is the opposite situation from that of the multi hole waveguide coupler.

4. Ribblet short-slot coupler consists of two waveguides that are separated by a distance “d”.
a) True
b) False

View Answer

Answer: b [Reason:] This coupler consists two waveguides with a common side wall. Coupling takes place in the region where part of the common wall has been removed.

5. Riblet-short slot coupler allows only:
a) TE10 mode of propagation
b) TE20 mode of propagation
c) Both a and b
d) None of the mentioned

View Answer

Answer: c [Reason:] In the part where common wall has been removed in this coupler, both the TE10 and TE20 mode are excited, and by proper design can be made to cause cancellation at the isolated port and addition at the coupled port.

6. Symmetric tapered coupled line couplers offer higher bandwidth when compared to other forms of couplers.
a) True
b) False

View Answer

Answer: a [Reason:] Multisection coupled line coupler can be extended to a continuous taper, yielding couple line couplers with good bandwidth characteristics.

7. The coupling and directivity of couplers with apertures in planar lines can be adjusted as per the requirement of the application.
a) True
b) False

View Answer

Answer: a [Reason:] In symmetric tapered coupled line coupler both the conductor width and separation between them can be adjusted to provide a synthesized coupling or directivity response. This can be tested with computer optimization of a stepped-section approximation to a continuous taper.

8. _________ is a key component in the scalar or vector network analyzer.
a) Reflectometer
b) Radiometer
c) Frequency meter
d) None of the mentioned

View Answer

Answer: a [Reason:] Reflectometer is a circuit that uses a directional coupler to isolate and sample the incident and reflected powers from the load. This is one of the key components in a scalar or vector network analyzer.

9. Reflectometer can also be used as a frequency meter.
a) True
b) False

View Answer

Answer: a [Reason:] Reflectometers can be used to measure the scattering parameters of a two port network. It is also used as SWR meter and also as power monitor in system applications.

10. A basic Reflectometer circuit can be used to measure the _____________ magnitude of the unknown load.
a) Reflection coefficient
d) Standing wave ratio
c) Transmission coefficient
d) None of the mentioned

View Answer

Answer: a [Reason:] A basic Reflectometer circuit can be used to measure the reflection coefficient magnitude of the unknown load. This is one of the major applications of Reflectometer. If the reflection coefficient is measured, the unknown load can be easily computed.

Set 3

1. A ___________ is any variable whose value depends on how the process takes place.
a) Path variable
b) State variable
c) Neither Path nor State variable
d) None of the mentioned

View Answer

Answer: a [Reason:] A Path variable is any variable whose value depends on how the process takes place.

2. Which one is not a path variable?
a) Work
b) Heat
c) Internal Energy
d) None of the mentioned

View Answer

Answer: c [Reason:] Internal energy does not depend on the path.

3. Any variable whose value depends only on the state of the system is called
a) Path variable
b) State variable
c) Neither Path nor State variable
d) None of the mentioned

View Answer

Answer: b [Reason:] A State variable is any variable whose value depends only on the state, not on the previous history.

4. Which one is a state variable ?
a) Internal Energy
b) Enthalpy
c) Entropy
d) All of the mentioned

View Answer

Answer: d [Reason:] All a, b, c are state variables as these are only depended only on the state, not on the history.

5. For an adiabatic system, two statements are given as following
I: The system is insulated
II: The process takes place so fast that there is no time for heat to be transferred.
a) Only I is correct
b) Only II is correct
c) Both I & II are correct
d) Neither I nor II correct

View Answer

Answer: c [Reason:] Both I and II are the properties of an Adiabatic system.

6. Which one is an intensive variable?
a) Pressure
b) Temperature
c) Volume
d) All of the mentioned

View Answer

Answer: d [Reason:] All three Pressure, Temperature and Volume are intensive variables as these are not depended on the path .

7. Heat transfer is caused by
a) Pressure difference
b) Temperature difference
c) Volume difference
d) None of the mentioned

View Answer

Answer: b [Reason:] Heat transfer is caused by Temperature difference.

8. Heat is ___________ when transferred to a system.
a) Positive
b) Negative
c) Zero
d) None of the mentioned

View Answer

Answer: a [Reason:] Heat is Positive when transferred to a system.

9. Heat is negative when transferred to the _____________
a) System
b) Surrounding
c) Boundary
d) None of the mentioned

View Answer

Answer: a [Reason:] Heat is negative when transferred to the surrounding .

10. A process in which no heat transfer takes place (Q=0) is
a) Isobaric process
b) Adiabatic process
c) Isothermal process
d) None of the mentioned

View Answer

Answer: b [Reason:] A process in which no heat transfer takes place (Q=0) is an Adiabatic process.

Set 4

1. Henry`s law is used primarily for a component whose mole fraction approaches_______
a) 0
b) 0.25
c) 0.50
d) 1.00

View Answer

Answer: a [Reason:] Henry`s law is used primarily for a component whose mole fraction approaches to zero.

2. Henry`s law can be applied to diluted gas dissolved in liquid.
The given statement is
a) Correct
b) Incorrect
c) Can`t predict
d) None of the mentioned

View Answer

Answer: a [Reason:] Henry`s law is used primarily for a component whose mole fraction approaches to zero.

3. For Henry`s law, Pi = HiXi, Here Pi is
a) Partial pressure in the gas phase of the dilute component
b) Vapour pressure in the gas phase of the dilute component
c) Total ambient pressure in the gas phase of the dilute component
d) None of the mentioned

View Answer

Answer: a [Reason:] Pi is the partial pressure in the gas phase of the dilute component.

4. For a dilute solution the relative lowering of vapour pressure is equal to mole fraction of solute. According to which law the statement is correct?
a) Henry`s Law
b) Dalton`s Law
c) Charles Law
d) None of the mentioned

View Answer

Answer: b [Reason:] Raoult’s law, for dilute solutions containing non-volatile solute, the relative lowering of vapour pressure is equal to the mole fraction of solute.

5. Positive deviation showing from Raoult’s law is?
a) Water – hydrochloric acid
b) Acetone – chloroform
c) Water – nitric acid
d) Benzene – methanol

View Answer

Answer: b [Reason:] Benzene – methanol mixture the intermolecular forces of attractions are weaker than those in pure liquids. Hence this mixture shows positive deviation.

6. The escaping tendency of a solvent is measured by its
a) Vapour pressure
b) Partial pressure
c) Ambient pressure
d) None of the mentioned

View Answer

Answer: a [Reason:] The escaping tendency of a solvent is measured by its Vapour pressure.

7. Vapour pressure is dependent on
a) Temperature
b) Pressure
c) Volume
d) None of the mentioned

View Answer

Answer: a [Reason:] Vapour pressure is dependent on Temperature.

8. Vapour pressure measures the concentration of solvent molecules in the ________ phase.
a) Gas
b) Liquid
c) Solid
d) None of the mentioned

View Answer

Answer: a [Reason:] Vapour pressure measures the concentration of solvent molecules in the Gas phase.

9. For an ideal solution the partial vapour pressure of a component in solution is equal to the mole fraction of that component times its vapour pressure. Is the
a) Henry`s Law
b) Dalton`s Law
c) Charles Law
d) Raoult`s LAw

View Answer

Answer: d [Reason:] Raoult’s law states that, for an ideal solution the partial vapour pressure of a component in solution is equal to the mole fraction of that component times its vapour pressure.

10. At high altitude the atmospheric pressure is
a) High
b) Low
c) Same as ground
d) None of the mentioned

View Answer

Answer: b [Reason:] At high altitude the atmospheric pressure is low.

Set 5

1. Statement 1: Glass packed food might be spoiled by light.
Statement 2: When canned foods with vacuum are taking onto flights, they _____
a) True, contract
b) True, expand
c) False, contract
d) False, expand

View Answer

Answer: b [Reason:] Glass packed food might be spoiled by light. When canned foods with vacuum are taking onto flights, they expand. This is because the pressure at high altitude that the flight tales off too is very low and inside the can is higher than outside and hence the bloating.

2. Statement 1: Raising the temperature of the room by 10 deg C will halve the storage life of that commodity.
Statement 2: Chemical reactions taking place during storage of canned foods will affect colour, texture and nutritive value of foods.
a) True, False
b) True, True
c) False, False
d) False, True

View Answer

Answer: b [Reason:] Raising the temperature of the room by 10 deg C will halve the storage life of that commodity. Chemical reactions taking place during storage of canned foods will affect color, texture and nutritive value of foods.

3. Which of the following does the critical point in a canning operation vary with?
a) Product packed
b) Container in which it is packed
c) Cooling and storage systems used
d) All of the mentioned

View Answer

Answer: d [Reason:] The critical point in a canning operation varies with all of the mentioned statements.

4. Statement 1: The ingredients, mixing, filling, sealing and retorting are processes that are checked for safe and well carried out canning operations.
Statement 2: The heat processes, cooling, handling and recording are processes that are checked for safe and well carried out canning operations.
a) True, False
b) True, True
c) False, False
d) False, True

View Answer

Answer: b [Reason:] Both the given statements are true.

5. Which of the following test does the seal of food item go through?
a) Fusion testing
b) Burst testing
c) Tensile testing
d) All of the mentioned

View Answer

Answer: d [Reason:] All of the mentioned are the tests the seal of a food item goes through.

6. Which of the following test should a retort pouch of food item pass through?
a) Visual examination
b) Resistance of pouches to high temperatures
c) Durable pouches with a high shelf life
d) All of the mentioned

View Answer

Answer: d [Reason:] All of the mentioned tests should a retort pouch of food item pass through.

7. Death rate in minutes of the bacteria at a particular temperature with respect to the formula by Stumbo is directly proportional to _____
a) Heating time in minutes
b) Initial number of spores
c) Number of positive TDT cans or tubes at a time
d) All of the mentioned

View Answer

Answer: a [Reason:] Death rate in minutes of the bacteria at a particular temperature with respect to the formula by Stumbo is directly proportional to heating time in minutes. It is indirectly proportional to the initial number of spores and number of positive TDT cans or tubes at a time.

8. A lower z value means that the spores are _____ resistant to a given C value.
a) More
b) Less
c) Neither of the mentioned
d) Cannot be predicted

View Answer

Answer: a [Reason:] A lower z value means that the spores are more resistant to a given C value.

9. Which of the following agitations in processing vacuum packaged vegetables has been reported?
a) Continuous end-over-end rotation
b) Continuous axial rotation
c) Intermittent axial rotation
d) All of the mentioned

View Answer

Answer: d [Reason:] All of the mentioned agitations in processing vacuum packaged vegetables have been reported.

10. Statement 1: A reduction in processing time is obtained when cans are maintained bottom down and perpendicular to the axis of rotation.
Statement 2: Rotational and reciprocal movements can reduce the heat penetration time to almost half the value.
a) True, False
b) True, True
c) False, False
d) False, True

View Answer

Answer: b [Reason:] A reduction in processing time is obtained when cans are maintained bottom down and perpendicular to the axis of rotation. Rotational and reciprocal movements can reduce the heat penetration time to almost half the value.

11. When the speed of centrifugation of food is such that it equals to the weight of the liquid contents, the head space void passes through approximately the center of the can.
a) True
b) False

View Answer

Answer: a [Reason:] When the speed of centrifugation of food is such that it equals to the weight of the liquid contents, the head space void passes through approximately the center of the can.

12. Advantage of agitation _____
a) Reduces the time of exposure for heat penetration
b) Successful canning of low acid foods in large containers
c) Higher temperatures may be used with lesser danger of cooking
d) All of the mentioned

View Answer

Answer: d [Reason:] All of the mentioned statements are advantages of agitation.

13. Disadvantage of agitation _____
a) Improved retention quality
b) Improved color and texture of product
c) Small canning operations in processing relatively unexploited heat sensitive food products
d) None of the mentioned

View Answer

Answer: [Reason:] Disadvantage of agitation is all of the mentioned statements.

14. Which of the following is true about end-over-end rotation?
a) Rate of penetration is slightly influenced by the speed of rotation
b) For large sized cans, placing the can adjacent to the axis of rotation allows maximum rotation
c) Both of the mentioned
d) Neither of the mentioned

View Answer

Answer: c [Reason:] Both of the mentioned is true about end-over-end rotation.

15. Which of the following step is included in food canning by sterilization, which is considered the ideal method for food canning?
a) Sterilization by heating and cooling by a tubular heat exchanger
b) Sterilization of containers and covers with super heated steam
c) Filling of sterile product into the sterile container, application of sterile covers to filled containers and sealing cans in an atmosphere of either saturated or super heated steam
d) All of the mentioned

View Answer

Answer: d [Reason:] All of the mentioned steps are included in food canning by sterilization, which is considered the ideal method for food canning.