Multiple choice question for engineering
Set 1
1. Basically sound waves are ______________
a) Voltage signals
b) Pressure waves
c) Current
d) Radiation
Answer
Answer: b [Reason:] Sound waves are pressure waves in character.
2. Which of the following is not a character of sensor of sound wave?
a) Causes no health hazard
b) They are suitable in harsh environment
c) They are only suitable in cold environment
d) They can be used in corrosive environment
Answer
Answer: c [Reason:] Sound sensors can be used in any environment.
3. Sound waves are similar to light waves in all aspects.
a) True
b) False
Answer
Answer: b [Reason:] While considering reflection and refraction, sound waves and light waves are similar.
4. SONAR stands for _______________
a) Sound navigation and ranging
b) Sound number approximation and ranging
c) Sound nullifying ranging
d) None of the mentioned
Answer
Answer: a [Reason:] Sonar is the short form of sound navigation and ranging.
5. Which of the following type sound generators are not possible?
a) Piezo electric
b) Magnetostrictive
c) Both piezo electric and magnetostrictive
d) None of the mentioned
Answer
Answer: d [Reason:] Both piezo electric and magnetostrictive devices are successful sources of sound waves.
6. Mosaic regarding sonar is ____________
a) Surface of sonar
b) Frequency of sound wave
c) Pattern of vibrating elements
d) Depth of sea to which it is applicable
Answer
Answer: c [Reason:] Specific pattern of vibrating element is known as msaic.
7. All elements of sonar are driven electrically.
a) True
b) False
Answer
Answer: a [Reason:] All elements of sonar are driven electrically using external power supply.
8. Piezo electric materials are well cut for _____________
a) Good dimension
b) Good coupling coefficient
c) Compact shape of device
d) Increasing frequency
Answer
Answer: b [Reason:] Piezo electric materials are so cut as to have maximum coupling coefficient between mechanical strain and electrical polarization direction.
9. Which of the following can be used in sonar?
a) ADP
b) Rescelle salt
c) ADP and Roscelle salt
d) ADP and Roscelle salt in sealed condition
Answer
Answer: d [Reason:] ADP and Roscelle salt are used as sealed with oil since they are soluble in water.
10. Magnetostriction transmitter uses _______________
a) Electrostrictive phenomena
b) Horizontal vibration of nickel tube
c) Longitudinal vibration of nickel tube
d) All of the mentioned
Answer
Answer: c [Reason:] Magnetostriction transmitter uses longitudinal vibration of nickel tube used.
Set 2
1. TTL stands for __________________
a) Transistor-triode-logic
b) Triode-transistor-logic
c) Triode-triode-logic
d) Transistor-transistor-logic
Answer
Answer: d [Reason:] TTL is the simplified for of transistor-transistor-logic and it is a circuit type of IC.
2. Which of the following is correct for digital devices?
a) Single stable logic level
b) Double stable logic level
c) Triple stable logic level
d) Infinite stable logic level
Answer
Answer: b [Reason:] A typical digital logic device have two stable logic level, high and low levels.
3. Which of the following gate act as inverter?
a) AND gate
b) OR gate
c) NOT gate
d) NAND gate
Answer
Answer: c [Reason:] NOT gate is an inverter in which output is the logically inverted form of input.
4. Unity-gain amplifier is the equivalent of _______________
a) Inverter
b) Driver
c) Amplifier
d) Rectifier
Answer
Answer: b [Reason:] Driver is the equivalent of unity-gain amplifier, which simply presents the logic state of the input at the output terminal.
5. Which of the following represents ‘inhibit’ gate?
a) AND gate
b) NAND gate
c) OR gate
d) NOR gate
Answer
Answer: a [Reason:] An inhibit gate is AND gate with one of its input terminal being preceded by an inverter.
6. In op-amp IC negative saturation is defined by______________
a) Logic High
b) Logic Low
c) Inverter
d) None of the mentioned
Answer
Answer: b [Reason:] In simpler logic circuit of op-amp, logic low state is defined by negative saturation operation.
7. Which of the following is equivalent to voltage-controlled switch?
a) Inverter gate
b) Drier gate
c) Transmission gate
d) None of the mentioned
Answer
Answer: c [Reason:] Transmission gate act as voltage controlled switch, which allows bidirectional flow of pulses.
8. Identify the gate?
| A | B | Q |
| 1 | 0 | 1 |
| 0 | 0 | 0 |
| 1 | 1 | 0 |
| 0 | 1 | 0 |
a) AND gate
b) INHIBIT gate
c) XOR gate
d) XNOR gate
Answer
Answer: b [Reason:] INHIBIT gate is an AND with one of its input terminals being preceded by an inverter.
9. OR gate has high output if ____________
a) One input is low
b) One input is high
c) All of the mentioned
d) None of the mentioned
Answer
Answer: b [Reason:] If one of the input is high, OR gate shows high output.
10. Driver has high output level when____________
a) Input is high
b) Input is high
c) All of the mentioned
d) None of the mentioned
Answer
Answer: b [Reason:] Driver follows the input and shows high output for high input state.
Set 3
1. Ozone layer is in earth layer ______________
a) Toposphere
b) Ionosphere
c) Stratosphere
d) Mesosphere
Answer
Answer: c [Reason:] Ozone layer is mainly seen in stratosphere.
2. CFC causes ozone layer depletion.
a) True
b) False
Answer
Answer: a [Reason:] Chloro flouro carbon or CFC causes ozone layer depletion.
3. Ozone depletion is higher at _______________
a) Polar regions
b) Near polar regions
c) Non polar regions
d) None of the mentioned
Answer
Answer: a [Reason:] Ozone depletion rate of polar regions are higher than any other regions due to motion of air.
4. Which of the following is not poisonous to humans?
a) Flue gases
b) Stack gases
c) HCl
d) None of the mentioned
Answer
Answer: d [Reason:] Flue gases, stack gases and HCl are poisonous to humans.
5. Toxic gases such as H2S, nitrogen oxides causes ____________
a) Immediate harm to body
b) Slow harm to body
c) Not sure about speed of action
d) None of the mentioned
Answer
Answer: a [Reason:] Toxic gases such as H2S, Notrogen oxides and CO causes immediate harm to human body.
6. NPL stands for _________________
a) National population laboratory
b) National pollution laboratory
c) National physical laboratory
d) Net pollution list
Answer
Answer: c [Reason:] Npl stands for national physical laboratory.
7. VOC stands for _______________
a) Viable organic components
b) Volatile organic components
c) Varying organic components
d) Virtual organic carriage
Answer
Answer: a [Reason:] VOC or volatile organic components emitted by sources are harmful to human.
8. Which of the following represents allowed rate of CO2?
a) Less than 5000ppm
b) Less than 700ppm
c) Less than 300ppm
d) Less than 100ppm
Answer
Answer: c [Reason:] CO2 rate above 300ppm causes harm to human body.
9. Long path optical measurement uses _____________
a) IR radiation
b) Ultraviolet radiation
c) Both IR and UV
d) None of the mentioned
Answer
Answer: c [Reason:] Long path optical measurement of pollution uses IR radiation or ultraviolet radiation.
10. Long path optical measurement have a range of several kilometres.
a) True
b) False
Answer
Answer: a [Reason:] Range of long path optical measurement varies from several meters to several kilometres.
Set 4
1. The height of a Watt’s governor (in metres) in equal to
a) 8.95/N2
b) 89.5/N2
c) 895/N2
d) 8950/N2
Answer
Answer: c [Reason:] Height of a Watt governor = g/ω2
= 9.81/(2πN/60)2
= 895/N2
where N = Speed of the arm and ball about the spindle axis.
2. The ratio of the height of a Porter governor (when the length of arms and links are equal) to the height of a Watt’s governor is
a) m/m+M
b) M/m+M
c) m + M/m
d) m + M/M
Answer
Answer: c [Reason:] Mass of the central load (M) increases the height of governor in the ratio m + M/m
where m = Mass of the ball, and
M = Mass of the load on the sleeve.
3. When the sleeve of a Porter governor moves upwards, the governor speed
a) increases
b) decreases
c) remains unaffected
Answer
Answer: a [Reason:] When the loaded sleeve moves up and down the spindle, the frictional force acts on it in a direction opposite to that of the motion of sleeve. The + sign is used when the sleeve moves upwards or the governor speed increases and negative sign is used when the sleeve moves downwards or the governor speed decreases.
4. A Hartnell governor is a
a) pendulum type governor
b) spring loaded governor
c) dead weight governor
d) inertia governor
Answer
Answer: b [Reason:] Since in hartnell governor spring is used, therefore it is the spring loaded governor.
5. Which of the following governor is used to drive a gramophone ?
a) Watt governor
b) Porter governor
c) Pickering governor
d) Hartnell governor
Answer
Answer: c [Reason:] A Pickering governor is mostly used for driving gramophone. It consists of three straight leaf springs arranged at equal angular intervals round the spindle. Each spring carries a weight at the centre. The weights move outwards and the springs bend as they rotate about the spindle axis with increasing speed.
6. Which of the following is a spring controlled governor?
a) Hartnell
b) Hartung
c) Pickering
d) all of the mentioned
Answer
Answer: d
7. For two governors A and B, the lift of sleeve of governor A is more than that of governor B, for a given fractional change in speed. It indicates that
a) governor A is more sensitive than governor B
b) governor B is more sensitive than governor A
c) both governors A and B are equally sensitive
d) none of the mentioned
Answer
Answer: a [Reason:] The greater the lift of the sleeve corresponding to a given fractional change in speed, the greater is the sensitiveness of the governor. It may also be stated in another way that for a given lift of the sleeve, the sensitiveness of the governor increases as the speed range decreases.
8. The sensitiveness of a governor is given by
a) ωmean/ω2 – ω1
b) ω2 – ω1/ ωmean
c) ω2 – ω1/ 2ωmean
d) none of the mentioned
Answer
Answer: b [Reason:] Let N1 = Minimum equilibrium speed,
N2 = Maximum equilibrium speed, and
N = Mean equilibrium speed = N1 + N2 / 2
Sensitiveness of the governor = N1 – N2 / 2
= 2(N1 + N2) / N1 + N2
= ω2 – ω1/ ωmean
where ω1 and ω2 = Minimum and maximum angular speed, and
ωmean = Mean angular speed.
9. In a Hartnell governor, if a spring of greater stiffness is used, then the governor will be
a) more sensitive
b) less sensitive
c) isochronous
d) none of the mentioned
Answer
Answer: b [Reason:] Stiffness is directly proportional to sensitiveness. Therefore, it stifness is greater, the governor will be less sensitive.
10. A governor is said to be hunting, if the speed of the engine
a) remains constant at the mean speed
b) is above the mean speed
c) is below the mean speed
d) fluctuates continuously above and below the mean speed
Answer
Answer: d [Reason:] A governor is said to be hunt if the speed of the engine fluctuates continuously above and below the mean speed. This is caused by a too sensitive governor which changes the fuel supply by a large amount when a small change in the speed of rotation takes place.
11. A hunting governor is
a) more stable
b) less sensitive
c) more sensitive
d) none of the mentioned
Answer
Answer: c
12. Isochronism in a governor is desirable when
a) the engine operates at low speeds
b) the engine operates at high speeds
c) the engine operates at variable speeds
d) one speed is desired under one load
Answer
Answer: d [Reason:] The isochronous governor is not of practical use because the sleeve will move to one of its extreme positions immediately the speed deviates from the isochronous speed.
13. The power of a governor is equal to
a) (c2/1 + 2c )(m + M) h
b) (2c2/1 + 2c )(m + M) h
c) (3c2/1 + 2c )(m + M) h
d) (4c2/1 + 2c )(m + M) h
Answer
Answer: d
14. When the relation between the controlling force (FC) and radius of rotation (r) for a spring controlled governor is FC = a.r + b, then the governor will be
a) stable
b) unstable
c) isochronous
d) none of the mentioned
Answer
Answer: b [Reason:] For the governor to be stable, the controlling force (FC) must increase as the radius of rotation (r) increases, i.e. FC / r must increase as r increases.
15. For a governor, if FC is the controlling force, r is the radius of rotation of the balls, the stability of the governor will be ensured when
a) dFC /dr > FC/r
b) dFC /dr < FC /r
c) dFC /dr = 0
d) none of the mentioned
Answer
Answer: a
Set 5
1. A disc is spinning with an angular velocity ? rad/s about the axis of spin. The couple applied to the disc causing precession will be
a) 1/2Iω2
b) Iω2
c) 1/2 Iω ωp
d) Iω ωp
Answer
Answer: d [Reason:] Since the rate of change of angular momentum will result by the application of a couple to the disc, therefore the couple applied to the disc causing precession,
Iω ωp
where I = Mass moment of inertia of the disc, and
ωp = Angular velocity of precession of the axis of spin.
2. A disc spinning on its axis at 20 rad/s will undergo precession when a torque 100 N-m is applied about an axis normal to it at an angular speed, if mass moment of inertia of the disc is the 1 kg-m2
a) 2 rad/s
b) 5 rad/s
c) 10 rad/s
d) 20 rad/s
Answer
Answer: b [Reason:] Gyroscopic couple acting on the disc,
C = I. ω. ωp
100 = 1 . 20. ωp
ωp = 100/1.20
= 5 rad/s
3. The engine of an aeroplane rotates in clockwise direction when seen from the tail end and the aeroplane takes a turn to the left. The effect of the gyroscopic couple on the aeroplane will be
a) to raise the nose and dip the tail
b) to dip the nose and raise the tail
c) to raise the nose and tail
d) to dip the nose and tail
Answer
Answer: a [Reason:] When the engine or propeller rotates in anticlockwise direction when viewed from the rear or tail end and the aeroplane takes a left turn, then the effect of reactive gyroscopic couple will be to dip the nose and raise the tail of the aeroplane. When the aeroplane takes a right turn, the effect of reactive gyroscopic couple will be to raise the nose and dip the tail of the aeroplane.
4. The air screw of an aeroplane is rotating clockwise when looking from the front. If it makes a left turn, the gyroscopic effect will
a) tend to depress the nose and raise the tail
b) tend to raise the nose and depress the tail
c) tilt the aeroplane
d) none of the mentioned
Answer
Answer: b [Reason:] When the engine or propeller rotates in clockwise direction when viewed from the front and the aeroplane takes a left turn, then the effect of reactive gyroscopic couple will be to raise the tail and dip the nose of the aeroplane. When the aeroplane takes a right turn, the effect of reactive gyroscopic couple will be to raise the nose and dip the tail of the aeroplane.
5. The rotor of a ship rotates in clockwise direction when viewed from the stern and the ship takes a left turn. The effect of the gyroscopic couple acting on it will be
a) to raise the bow and stern
b) to lower the bow and stern
c) to raise the bow and lower the stern
d) to lower the bow and raise the stern
Answer
Answer: c [Reason:] When the rotor rotates in the clockwise direction when viewed from the bow or fore end and the ship is steering to the left, then the effect of reactive gyroscopic couple will be to raise the stern and lower the bow.
6. When the pitching of a ship is upward, the effect of gyroscopic couple acting on it will be
a) to move the ship towards port side
b) to move the ship towards star-board
c) to raise the bow and lower the stern
d) to raise the stern and lower the bow
Answer
Answer: b [Reason:] The effect of the gyroscopic couple is always given on specific position of the axis of spin i.e. whether it is pitching downwards or upwards. The pitching of a ship produces forces on the bearings which act horizontally and perpendicular to the motion of the ship.
7. In an automobile, if the vehicle makes a left turn, the gyroscopic torque
a) increases the forces on the outer wheels
b) decreases the forces on the outer wheels
c) does not affect the forces on the outer wheels
d) none of the mentioned
Answer
Answer: a [Reason:] The gyroscopic couple will act over the vehicle outwards i.e. in the anticlockwise direction when seen from the front of the vehicle. The tendency of this couple is to overturn the vehicle in outward direction.
8. A motor car moving at a certain speed takes a left turn in a curved path. If the engine rotates in the same direction as that of wheels, then due to the centrifugal forces
a) the reaction on the inner wheels increases and on the outer wheels decreases
b) the reaction on the outer wheels increases and on the inner wheels decreases
c) the reaction on the front wheels increases and on the rear wheels decreases
d) the reaction on the rear wheels increases and on the front wheels decreases
Answer
Answer: b [Reason:] When the engine is rotating in the same direction as that of wheels, then the positive sign is used in the above expression and if the engine rotates in opposite direction, then negative sign is used.