1. A certain appliance uses 700 W. If it is allowed to run continuously for 36 days, how many kilowatt-hours of energy does it consume(up to 1 deci)
ANS:- 700*36*24/1000=604.8
2. Alfa particles enter an electromagnetic field where the electric intensity is 300v/m and the magnetic induction is 0.200T what is the velocity of Alfa particles
F=qvB V=F/qB=300/2*.2=750 charge of an alfa particle is 2
3. What is the magnetomotive force ina 75 turn coil of wire when ther are 4A of current through it?
F=NI=75*4=300Ampere turn AT
4. Resistances of 20,15,25 ohm are connected in series across a 36 v line.calculate voltage drop across 25 ohm resistance
R=20+15+25=60 V/R=I=36/60=0.6 V=RI=.6*25=15
5. Two pole motor running at 4800 rpm calculate frequency
N=120f/p F=NP/120=4800*2/120=80
6. A poly phase motor driving an engine room pump fails to start, when trying to identify the cause of failure, which of the following steps are applicable.(multiple ans)
A. visually examine the motor for open circuit fault
B. visually examine the stator for open circuit fault
C. Reverse the direction of current for its working
D. Perform the infinite resistance test
7.If an intrinsic semiconductor is doped with a very small amount of boron then the extrinsic semiconductor set formed, the no. of electrons and holes will
A.both Dec.
B.increase and decrease
C.Both increase
D.Decrease and increase
8.In what range of voltages is the transistor in the linear region of its operation?
A.0 < VCE < 0.7 V
B.0.7 < VCE < 1.4 V
C.0.7 < VCE < VCE(max)
D.0 < VCE < VCE(max)
9.The current in a semiconductor is produced by:
A. Electrons
B. Neutrons
C. Protons
D. Holes
10.Brushless generators are designed to operate without the use of
A.brushes
B. sliprings
C. commutators
D. all of the above
11.Where a thermal-acting breaker is required to be used in an area of unusually high, low, or constantly
fluctuating temperatures, an ambient compensating element must be used. This element consists of a
A. Cylindrical spring on the contact arm.
B. Conical spring on the contact arm.
C. Second bimetal element.
D. Second electromagnet.
12.A fuse that blows often should be replaced only with a fuse of
A. the recommended current and voltage rating
B. higher current and voltage rating
C. higher current and lower voltage rating
D. lower current and higher voltage rating
13.Which of the listed precautions should be taken when cleaning the internals of a motor with compressed
air?
A. Open the machine on both ends so as to allow the air and dust to escape.
B. Be certain that the circuit breaker is opened and tagged on the feeder panel.
C. Be certain that the air is clean and as dry as possible.
D. Ensure that the fuse in the motor is removed.
14.Fuses placed in series with a thermal trip = - type circuit breaker are used for
A. Time-delay protection
B. Short-circuit protection
C. Short duration surge protection
D. Sustained overload protection
15.A molded-case breaker provides protection against short-circuits by usinga/an
A. Shading coil.
B. Arc quencher.
c.Electromagnet.
D.Holding coil.
16.The induced voltage across a stationary conductor in a steady magnetic field is zero.
A.True
B.False
17.When paralleling an AC generator with live bus bars, which of the following precautions are applicable? ^
A. Generator firequency should be slightly lower than bus bar frequency
B. Generator frequency should be slightly higher than bus bar frequency
C. Generator voltage should be in phase with bus bar voltage
D. Generator voUage should be out of phase with bus bar voltage ""^
18.Tightly knit metal braid wire can be used with a printed circuit board when
A. Conductor flexibility is required
B. De-soldering components in the circuit
C. Electrically produced magnetic fluxes would cause inaccuracies in adjacent components
D. Reactance in the circuit must be kept to a minimum
19.A poly-phase motor driving an engine room pump fails to start. When trying to identify the cause of
failure, which of the following steps are applicable?
A. Visually examine motor for open circuit faults.
B. Visually examine starter for open circuit faults.
C. Reverse the direction of electrical supply to check if it works.
D. Perform the infinite resistance test.
20.AC circuits possess characteristics of resistance, inductance, and capacitance.The capacitive reactance of
acircuit is expressed in
A. ohms
B. mhos
C. hemys
D. farads
23. The greatest detrimental effect on idle electrical equipment, such as cargo pump motors,is the
24.1f it takes 35 J of energy to move a charge of 6 C from one point to another, what is the voltage between the two points? Your answer should be correct to two decimals.
V=E/Q=35/6=5.83V
25.Which of the following statements is true concerning a poly-phase synchronous propulsion motor?
26.When reading electrical motor controller diagrams, it helps to know that .
27. Large cable sizes are formed as individual conductors that may be comprised of several smaller strands to .
28.Which of the following is having Di-Electric Constant 80?
29.Where a thermal-acting breaker is required to be used in an area of unusually high, low, or constantly
30. A semiconductor that decreases in resistance with an increase in temperature is known as a
31. In a diesel electric plant, raising the generator's field excitation will cause the DC propulsion motor to
33.The part of a fuse that melts and opens the circuit is made of .
34.A synchronous motor maintains synchronism with the rotating field because .
35. Silicon diodes designed for a specific reverse breakdown voltage, become useful as an electronic power supply voltage regulator, called.............
36.Time delayed or delayed action-type fuses are designed to .
37. PN DIODE ADVANTAGE OVER VACUUM DIODE ?
38.Electrons and protons of the same momentum enter normally into a uniform magnetic field of flux density B. mass of the electron is me (m suffix e) and mass of the proton is mp (m suffix p).if re (r suffix e) and rp (r suffix p) represents the radii of the path of the electrons and the protons respectively, calculate the ratio re/rp. your answer should be correct to 2 decimals..
F=qvB=mv2/r qB=mv/r
39.The opposition to the magnetic lines of force in magnetic field is called
40.Determine the order of doping in transistor (from high to low)
41.A low voltage protection circuit is used in electric motor starting equipment to
42.Which of the following capacitor is having highest di electric constant
43.Which of the following conditions will occur when solenoid coil bums out of a cargo winch with a electrical brake.
44.Which of the following physical character does around rotor induction motor posses that squirrel cage motor does not
45. To prevent electric shock during electric arc welding
46.Getting the value of a/c sign wave from ammeter and voltmeter is
47.The appereant power in inductive circuit
48.purpose of preferential trip to prevent
49.which of the capacity has dielectric constant of 1.0000
50.When testing a capacitor with an analog type ohmmeter, a good capacitor will be indicated when
51.For a given line voltage, four heating coils will produce maximum heat when connected in
52.A semiconductor is damaged by a strong current, because of (1)------ (2)------ (3)-------
Ans: over load ,over current ,short circuit
53.what happens to the strength of electro magnetic field when current passing through an inductor is half__________-
54.Open-loop transfer function of a system having one zero with positive real values is called ------
ANS: phase function
55.The direction of induced EMF can be found with the help of -----
ANS:- 700*36*24/1000=604.8
2. Alfa particles enter an electromagnetic field where the electric intensity is 300v/m and the magnetic induction is 0.200T what is the velocity of Alfa particles
F=qvB V=F/qB=300/2*.2=750 charge of an alfa particle is 2
3. What is the magnetomotive force ina 75 turn coil of wire when ther are 4A of current through it?
F=NI=75*4=300Ampere turn AT
4. Resistances of 20,15,25 ohm are connected in series across a 36 v line.calculate voltage drop across 25 ohm resistance
R=20+15+25=60 V/R=I=36/60=0.6 V=RI=.6*25=15
5. Two pole motor running at 4800 rpm calculate frequency
N=120f/p F=NP/120=4800*2/120=80
6. A poly phase motor driving an engine room pump fails to start, when trying to identify the cause of failure, which of the following steps are applicable.(multiple ans)
A. visually examine the motor for open circuit fault
B. visually examine the stator for open circuit fault
C. Reverse the direction of current for its working
D. Perform the infinite resistance test
7.If an intrinsic semiconductor is doped with a very small amount of boron then the extrinsic semiconductor set formed, the no. of electrons and holes will
A.both Dec.
B.increase and decrease
C.Both increase
D.Decrease and increase
8.In what range of voltages is the transistor in the linear region of its operation?
A.0 < VCE < 0.7 V
B.0.7 < VCE < 1.4 V
C.0.7 < VCE < VCE(max)
D.0 < VCE < VCE(max)
9.The current in a semiconductor is produced by:
A. Electrons
B. Neutrons
C. Protons
D. Holes
10.Brushless generators are designed to operate without the use of
A.brushes
B. sliprings
C. commutators
D. all of the above
11.Where a thermal-acting breaker is required to be used in an area of unusually high, low, or constantly
fluctuating temperatures, an ambient compensating element must be used. This element consists of a
A. Cylindrical spring on the contact arm.
B. Conical spring on the contact arm.
C. Second bimetal element.
D. Second electromagnet.
12.A fuse that blows often should be replaced only with a fuse of
A. the recommended current and voltage rating
B. higher current and voltage rating
C. higher current and lower voltage rating
D. lower current and higher voltage rating
13.Which of the listed precautions should be taken when cleaning the internals of a motor with compressed
air?
A. Open the machine on both ends so as to allow the air and dust to escape.
B. Be certain that the circuit breaker is opened and tagged on the feeder panel.
C. Be certain that the air is clean and as dry as possible.
D. Ensure that the fuse in the motor is removed.
14.Fuses placed in series with a thermal trip = - type circuit breaker are used for
A. Time-delay protection
B. Short-circuit protection
C. Short duration surge protection
D. Sustained overload protection
15.A molded-case breaker provides protection against short-circuits by usinga/an
A. Shading coil.
B. Arc quencher.
c.Electromagnet.
D.Holding coil.
16.The induced voltage across a stationary conductor in a steady magnetic field is zero.
A.True
B.False
17.When paralleling an AC generator with live bus bars, which of the following precautions are applicable? ^
A. Generator firequency should be slightly lower than bus bar frequency
B. Generator frequency should be slightly higher than bus bar frequency
C. Generator voltage should be in phase with bus bar voltage
D. Generator voUage should be out of phase with bus bar voltage ""^
18.Tightly knit metal braid wire can be used with a printed circuit board when
A. Conductor flexibility is required
B. De-soldering components in the circuit
C. Electrically produced magnetic fluxes would cause inaccuracies in adjacent components
D. Reactance in the circuit must be kept to a minimum
19.A poly-phase motor driving an engine room pump fails to start. When trying to identify the cause of
failure, which of the following steps are applicable?
A. Visually examine motor for open circuit faults.
B. Visually examine starter for open circuit faults.
C. Reverse the direction of electrical supply to check if it works.
D. Perform the infinite resistance test.
20.AC circuits possess characteristics of resistance, inductance, and capacitance.The capacitive reactance of
acircuit is expressed in
A. ohms
B. mhos
C. hemys
D. farads
21.Altemating ciirrent circuits develop resistance, inductance and
capacitance. The inductance of a coil is
expressed in .
A. ohms
B. mhos
C. henrys
D. farads
22.The basic measuring unit of inductance is the
A. coulomb
B. ohm
C. farad
D. henry
23. The greatest detrimental effect on idle electrical equipment, such as cargo pump motors,is the
A. Loss of residualmagnetism.
B. Absorption of moisture in the
insulation.
C. Insulation vamish flaking.
D. Dirt collecting on the windings. ^
24.1f it takes 35 J of energy to move a charge of 6 C from one point to another, what is the voltage between the two points? Your answer should be correct to two decimals.
V=E/Q=35/6=5.83V
25.Which of the following statements is true concerning a poly-phase synchronous propulsion motor?
A. The motor is started as an induction
motor.
B. Resistance is gradually added to the
rotor circuit.
C. The starting current is held below the
rated current.
D. The field winding is energized for starting purposes only.
26.When reading electrical motor controller diagrams, it helps to know that .
A. current paths in the control circuit
are drawn as heavy lines and in the power circuit as lighter lines
B. current paths in the power circuit are
drawn as heavy lines and in control circuit as lighter lines
C. circuits subject to 500 volts or
greater are drawn as heavy lines and below 500 volts as lighter lines
D. circuits subject to 500 volts or
greater are drawn as light lines and below 500 volts as heavy
27. Large cable sizes are formed as individual conductors that may be comprised of several smaller strands to .
A. obtain the flexibility required for
easy handling
B. reduce the overall weight of the wire
nm
C. reduce the number of supports needed
for a horizontal overhead run
D. all of the above
28.Which of the following is having Di-Electric Constant 80?
A. Air
B. water
C. Mica
D. Caster oil
29.Where a thermal-acting breaker is required to be used in an area of unusually high, low, or constantly
fluctuating temperatmes, an ambient
compensating element must be used. This element consists of a
A. cylindrical spring on the contact arm
B. conical spring on the contact arm
C. second bimetal element
D. second electromagnet
30. A semiconductor that decreases in resistance with an increase in temperature is known as a
A. resistor
B. thermistor
C. diode
D. thermopile
31. In a diesel electric plant, raising the generator's field excitation will cause the DC propulsion motor to
A increase in speed
B decrease in speed
e affect generator speed only
D affect main motor speed if done in
conjunction with higher generator engine speeds
32.Which of the following statements best describes the material known as
varnished cambric?
(A) Felted asbestos sealed with varnish.
(B) Cotton cloth coated with insulating
varnish.
(C) Rubber insulation coated with a layer
of tin.
(D) Paper impregnated with mineral oil,
specially wrapped with nonmetallic tape, and coated with varnish.
33.The part of a fuse that melts and opens the circuit is made of .
(A) Copper and antimony
(B) Steel and Babbitt
(C) Aluminum or beryllium alloy
(D) Zinc or an alloy of tin and lead
34.A synchronous motor maintains synchronism with the rotating field because .
(A) field strength varies directly with
rotors Up
(B) DC current applied to the rotor coils
causes the rotor magnets to lock in with the rotating flux of the stator
(C) the stator poles are dragged around
due to the flux created by the excitation current
(D) the stator flux rotates in the
opposite direction
35. Silicon diodes designed for a specific reverse breakdown voltage, become useful as an electronic power supply voltage regulator, called.............
(A) tunnel diodes
(B) hot-carrier diodes
(C) compensating diodes
(D) Zener diodes
36.Time delayed or delayed action-type fuses are designed to .
(A) prevent grounds in branch circuits
(B) prevent opens in motor circuits
(C) permit momentary overloads without
melting
(D) guard lighting and electronic circuits
37. PN DIODE ADVANTAGE OVER VACUUM DIODE ?
a) longer life
b) no warm up time
c) less delicate
d) all of the above
38.Electrons and protons of the same momentum enter normally into a uniform magnetic field of flux density B. mass of the electron is me (m suffix e) and mass of the proton is mp (m suffix p).if re (r suffix e) and rp (r suffix p) represents the radii of the path of the electrons and the protons respectively, calculate the ratio re/rp. your answer should be correct to 2 decimals..
ANS:-
charged particle describe an anticlockwise
circular path and magnetic force work as centripetal force. Thus
F=qvB=mv2/r qB=mv/r
Here MpV and MeV are
same because of same momentum
for electron qB=MeV/Re
for proton qB=MpV/Rp
dividing bothe equation Re/Rp=1.00
39.The opposition to the magnetic lines of force in magnetic field is called
A. Resistance
B. Reluctance
C. Impedence
D. Inductance
40.Determine the order of doping in transistor (from high to low)
A. collector .base, emitter
B. Emitter,collector,base
C. Base, emitter,collector
41.A low voltage protection circuit is used in electric motor starting equipment to
A. Trip circuit contractor when the motor
overspeed due to low voltage
B. Trip circuit contractor when the motor
develops short circuit due to low voltage
C. Allows the motor to restart
automatically on restoration of voltage without manual resetting
D. prevent motor from restarting
automatically
42.Which of the following capacitor is having highest di electric constant
A. air gap
B. glass
C. paper
D. polyster
43.Which of the following conditions will occur when solenoid coil bums out of a cargo winch with a electrical brake.
A. The brake will be set by spring
force.
B. The motor will over speed and bums out
C. The load suspended by the cargo boom
will fail
D. Nothing will happen, the winch will
continue to operate normally
44.Which of the following physical character does around rotor induction motor posses that squirrel cage motor does not
A. Slip rings
B. End rings
C. A centrifugal clutch
D. End plates
45. To prevent electric shock during electric arc welding
A. Wear dry clothes
B. Wear insulated shoes
C. Keep first aid equipment ready
D. None of the above
46.Getting the value of a/c sign wave from ammeter and voltmeter is
A. rms
B. Avg
C. Peak
47.The appereant power in inductive circuit
a truepower
b lead
c inductive
d reactive
48.purpose of preferential trip to prevent
a. blackout
b. to avoid overload
c. to start heavy machinery
d, all
49.which of the capacity has dielectric constant of 1.0000
a. airgap
b. vaccum
c. water
d. electrolytes
50.When testing a capacitor with an analog type ohmmeter, a good capacitor will be indicated when
A there is no meter deflection
B the meter deflects to a low resistance
value and remains there
C the meter deflects to a low resistance
value and slowly increases towards infinity
D the meter deflects to a low resistance
value and increases rapidly to a higher value, but stays fairly low
51.For a given line voltage, four heating coils will produce maximum heat when connected in
A. Parallel
B. series
C.same heat in both the time
D. none of the above
52.A semiconductor is damaged by a strong current, because of (1)------ (2)------ (3)-------
Ans: over load ,over current ,short circuit
53.what happens to the strength of electro magnetic field when current passing through an inductor is half__________-
a.1/4
b.1/2
c.2
d.4
54.Open-loop transfer function of a system having one zero with positive real values is called ------
ANS: phase function
55.The direction of induced EMF can be found with the help of -----
ANS: Lenz's law
Plz post new questions in comment box..... we will update it and collect all the asked questions in one point.... or mail us on marinesite.blogspot@gmail.com
question no 14 ans is b and not a
ReplyDeleterefer uscg q 177
corrections are always welcome..... plz post new question after your exam.... best wishes....
Delete1. *Open-loop transfer function of a system having one zero with positive real values is called nonminimum phase function is this correct?
ReplyDeleteSolve the equation for g(s)= (s^2 +3)/{(s^5)+(s^4)+(s^3)+(3s^2)+(2s)}?
ReplyDeletePS: From some closed loop system equation.