## Pages

### Ele S 4

Electrician theory sem 4 july 2015 questions

Which element is used as a semi conductor?
A Copper  B Silver  C Silicon  D Aluminium

The number of valance electrons of the germanium element is.................
A  5        B  4      C 3       D  2

Name the element used as impurity to produce 'N'- type semi conductor?
A Gallium  B Boron  C Aluminium  D Arsenic

The barrier potential voltage of silicon element is................
A 0.7 volt    B 0.6 volt    C 0.5 volt   D 0.3volt

In diode, the current, which can allow to flow through it without getting damaged is called as.............
A   maximum reverse current           B   maximum average forward current
C  maximum forward surge current  D  maximum load current

In diode terminology PIV stands for
A  Peak Instantaneous Voltage     B  Polarity Identification Value
C  Peak Inverse Voltage               D  Peak Inverse Value

A   Signal diodes                    B   Switching diodes
C   Point contact diodes          D   High power diodes

Aa per the PRO ELECTRON type coding, one diode is specified as 'BY127'. In this, what dose the letter T indicate?
A Power diode   B Rectifier diode    C Signal diode     D Junction diode

if the input AC voltage is 30 volts, then the output D.C voltage of the half wave rectifier will be...............
A  30.0 volt     B  27.0 volt   C  13.5 volt    D  10.8 volt

if the input AC frequency is 50 Hz then the output ripple frequency of the bridge rectifier is.........
A   50 Hz      B   100 Hz    C   150 Hz     D   200 Hz

Which type of filter can be used together with a full wave rectifier only?
A  Series Inductor filter    B  Pi filter (n)    C  RC filter    D  Choke input LC filter

What is the forward voltage drop of single green colour LED is..................
A  1.8 volt     B  2.0 volt    C  2.2 volt    D  2.1 volt

Which one is the application of high power transistor?
A Microphone   B Loud speaker   C Tape recorder   D Transducers

A transistor is designated as '2N 3055'. What does '2N' indicate?
A   Indicates as diode
B   Indicates the number of terminals
C   Indicates the field effect transistor
D   Indicates thetwo junction device (transistor)

In common emitter amplifier the output characteristic curves can be obtained by plotting...................
A lc on the 'Y' axis Vs VCE on the 'X' axis
B lB on the Y axis Vs V6E on the 'X' axis
C Vbe on the Y axis Vs le on the Y axis
D  VCE on the Y axis Vs lc on the Y axis

Which type of transistor biasing in commonly used in digital circuits?
A Self bias    B Base bias    C Voltage divider bias    D Emitter bias

The power gain (Ap) of amplifier is often expressed in..........
A milliwatts   B watts   C decibel   D percentage

The emitter follower configuration is frequently used as..................
A  an amplifier circuits                    B  switching circuits
C  negative feed back circuit            D  an impedance matching circuit

One of the application of class - A amplifier is...............
A  audio power amplifier circuit    B  micro phone    C  tape recorder    D  radio receiver

One of the disadvantages of the class - B push pull amplifier is....................
A   the single ended input and output   B   the positive half cycle only get amplified
C   having a cross - over distortion       D   having centre tapped drive transformer

If the output of the oscillator is non-sinusoidal wave form then, the type of oscillator is known as..................
A  relaxation oscillators   B  harmonic oscillators
C  colpitt's oscillators       D  hartley oscillator

Which type of oscillator is used in broad cast transmitters?
A  Hartley oscillator              B  Crystal oscillator
C  R-C phase shift oscillator  D  Colpitt's oscillator

The free running multi - vibrator is also known as...............
A bistable multi vibrator    B mono - stable multi vibrator
C astable multi-vibrator     D mono -shot

The noise in operational amplifiers can be reduced by...............
A  applying dual DC power supply
B  applying single D.C power supply
C  increasing the value of input resistor to large values
D  shortening the interconnecting wire lengths

The gain of an op - amp. is specified at different frequencies is termed as.........
A frequency gain   B gain - band width - product   C band width gain  D op - amp. Voltage gain

The application of UJT is..........
A filter circuits  B power amplifier  C relaxation oscillator  D sinusoidal oscillator

The material is used in solar cell as positive output terminal is................
A  nickel plated ring   B  chromium plated ring  C  silver coated ring  D  zinc plated ring

What are the terminal markings in TRIAC?
A  Source (S), Gate (G), Drain (D)
B   Main terminal -1 (MT1, Main terminal - 2 (MT2) Gate (G)
C   Base (B), Collector (C), Emitter (E)
D  Anode (1), Anode (2)

FET (Field Effect Transistor) is also known as.............
A  bi-polar transistor             B   unipolar transistor
C  current controlled device  D  power controlled device

GTO stands for..............
A  Gated Tuned - off Thyristor       B  Gate Turn - off Thyristor
C  Gain Triggered - off transistor    D  Gate Triggering - off Thyristor

One of the application of GTO is.............
A  high power amplifier   B  signal diodes   C  induction heating    D oscillators

IGBT stands for..............
A   Integrated Gate Bipolar Transistor  B   Intrinsic Gallium Bipolar Thyristor
C   Insulated Gate Bipolar Transistor   D   Integrated Gain Bipolar Thyristor

One of the application of IGBT is.....
A  inverters B multi vibrators C amplifiers D loudspeaker

The current through the load in SCR: wnich is below the critical value Is called as........
A  gate current B  forwarded current C  holding current D  load current

The main application of SCR is.............
A  the speed control of motors B  the voltage amplifier circuits C  the filter circuits D  the oscillator circuits

In MOSFET, the insulating layer is generally made of...................
A  galiium dioxide B  silicon dioxide C  germanium plate D  bismuth piate

SCR stands for................
A  Semi Conductor Rectifier             B  Speed Controlled Rectifier
C  Special Conductor Rectifier          D  Silicon Controlled Rectifier

The speed of the A.C motors using SCR can be controlled by varying..................
A the holding current of SCR    B  the firing angle of the SCR
C  the load current                    D the gate current

In IC type, voltage regulator, it is designated as 7805'. What does the number 78l indicate?
A The positive output regulator  B The negative output regulator
C The input positive voltage       D The output negative voltage

In a on - line UPS system, The switch over time from mains to battery is.................
A 10 milli sec    B  9 milli sec    C  8 milli sec   D  zero

In Binary number '0100' is equal to the decimal number is....................
A 1   B 2   C 3  D 4

The decimal number '8' is equal to the binary number is....................
A 1000  B 1001  C 0111  D 0110

in Hexadecimal number system the base number is.........
A 6  B 12  C 16  D 18

In Hexadecimal number system the letter 'D' indicates the decimal number is.........
A D=14   B D=13   C D=12   D D=11

The pre-dominant binary coded decimal code is...........
A 1248  B 2481   C 4286    D 8421

If the inputs of the 'OR' gate are 'A&B', then the output (y)=..........
A  y = A.B   B   y = A-B    C   y = A+B   D   y= AB

In J&K flip-flops the 16 clock pulse dives Q=..........
A 1111  B 0000   C 1001   D 1010

What are the two inputs (A&B) of the 'NOR' gate, if the output (y)=1?
A A=0;B=0     B A=0;B=1   C A=1;B=0    D A=1;B=1

ELECTRICIAN   (THEORY)
SEMESTER - IV JAN2018

If a slot consists of one coil side then the winding is called.......
a) Double layer winding
b) Full pitch winding
c) Single layer winding
d) Short pitch winding

A capacitor start, capacitor run single phase induction Inotor is basically a........
a) AC series b) DC series motor
c) 2 phase induction motor
d) 3 phase induction tnotor

The starting torque of' a capacitor start lü0tor is —
a) Zero
b) Low
c) Same as rated torque
d) More than rated torque

The starting capacitor of a single phase motor is......
a) Electrolytic capacitor
b) Ceramic capacitor
c) Paper capacitor
d) None of the above.

The motor used in household refrigerators is
a)  series Inotor
b) DC shunt motor
c) Universal Inotor
d) Single phase induction tnotor.

A capacitor start single phase induction motor will usually have a pov.er thctor of.......
a) Unity
d) 0.6 lagging

The short corning of repulsion motor is —
a) Variation of speed with load
b) Low power lhctor
c) Il'cndcncy to spark at brushes d) All of these

A ceiling fan, of 1  nun sweep will have motor rating or.......
a) 10 to 1 5 watts
b) 50 to 70 watts
c) 120 to 1 80 watts
b) 250 to 500 watts.

Which of the following applications would need the smallest size or motor?
a) Domestic motor
b) Electric clock
c) Table fan
d) Sewing machine

Which of the following is not a bio-mass source?
a) Gobar gas
b) Coal
c) Wood
d) Nuclear energy

The source of energy of the sun is
a) Nuclear fission
b) Chemical reaction
c) Nuclear fusion
d) Photoelectric effect

Which motor would you select for vacuum cleaners?
a) Universal motor
b) Repulsion motor
c) Hysteresis motor
d) Reluctance motor.

The advantage of salient poles in an alternator is.......
a) Reduce noise
b) Reduced windagc loss
c) Adoptability to low and medium speed operation
d) Reduce bearing loads and noise.

Major share of power generated in India is through which means-
a) Hydroelectric power plants
b) Nuclear power plants
c) Thermal power plants
d) Gas turbine power plants

A three phase alternator has a phase sequence of RYB for its three output voltages, for clockwise rotation. Now if the alternator is rotated anticlock wise. the phase sequence will be
a) RYB b) RBY
c) BYR d) None of these

In an alternator, voltage drops occurs in......
a) Armature resistance only
b) Armature resistance and leakage reactance
c) Armature resistance, leakage reactance and armature reaction
d) Annaturc resistance, leakage reactance. armature reaction and earth connections.

The power Factor of' an alternator depends on —
a) Load b) Speed of rotor
c) Core losses d) Armature losses

The frequency of voltage generated by an alternator having 8 poles and rotating at 250 rpm is........
a) 60 Hz.    b) 50 Hz
c) 25 Hz d) 16 2/3Hz

A winding is having number of slots is greater than munber of poles. then this winding is called-
a) Concentrated winding
b) Distributed winding
c) Full pitch winding
d) Integrated slot winding

Synchronous Inotor can operate at.......
a) Lagging power factor only
c) Unity power factor only
d) Lagging, leading and unity power factor only

The damping winding in a synchronous motor is generally used
a) To provide starting torque only
b) To reduce noise lcvcl
c) To reduce eddy currents
d) To prevent hunting and provide the starting torque

The back emf set up in the stator of a synchronous motor will depend on
a) Rotor speed only
b) Rotor excitation only
c) Rotor excitation and rotor speed
d) Coupling angle. rotor speed and excitation

In a synchronous motor, damper winding is provided to
a) Stabilize rotor Inotion
b) Suppress rotor oscillations
c) Develop necessary starting torque
d) Both (a) & (c)

Advantagc of hydro-elcctric power station is........
a) Low operating cost
b) Free from pollution probletns
c) No fuel transportation problems
d) All of these

An Auto-transformer (which has only one winding) may be used as a........
a) Step-Up Transformer
b) Step-Down Transformer
c) Both (a) & (b)
d) None of the above

26. In an Auto transformer, The Primary and Secondary are ....... Coupled
a) Only Magnetically
b) Only Electrically
c) Magnetically as well as Electrical
d)None of these

The nominal ratio for a current transformer is given by
a) (Rated primary winding current)/ (Rated secondary winding current)
b) (Number of turns in the primary winding) / (Number of turns in the secondary winding)
c) (Number of turns in the secondary winding)/ (Number of turns in the primary winding)
d) (Rated secondary winding current) / (Rated primary winding current)

The transformer ratio of the transformer depends upon the
a) Exciting current
b) Secondary current
c) Power factor of secondary circuit
d) All of these

Radiant efficiency of the luminous source depends on
a) Shape of the source
b) Temperature of the source
c) Wavelength of light rays
d) All of these

Carbon arc lamps arc commonly used in.........
a) Domestic lighting
b) Street lighting
c) Cinema projectors
d) Photography

The unit of solid angle is.........

Candela is the unit of ..........
a) Luminous flux
b) Luminous intensity
c) Wavelength
d) None of these

The unit of Iuminous flux is ......
b) Candela
c) Lumen
d) Lux

Luminous efficiency of a fluorescent tube is .......
a) 5- 10 lumens/watt
b) 15-20 lumens/watt
c) 30 - 40 lumens/watt.
d) 60-65 lumens/watt.

One lumen per square meter is the same as..........
a) One lux
b) One candela
c) One foot candle
d) One lumen meter

The frequency or (lickers in a fluorescent lamp at 220 V, 50 Hz supply will be.......
a) 25 per second
b) 50 per second
c) 100 per second
d) 220 per second

One that is based on forward biased PN junction is......
a) Photo diode.     b) LED
c) Photo voltaic cell
d) Both (a) & (b)

Photo diode is used for detection of .........
a) Visible light
b) Invisible light
c) No light
d) Both (a) & (b)

Color of light emitted by LED depends on......
a) Its forward bias
b) Its reverse bias
c) Forward current
d) Semiconductor material

The earth wire should not be thinner than a.......
a) 20 SWG wire b) 16 SWG wire
c) 10 SWG wire d) 8 SWG wire

In   the sound is produced by horn due to .......
a) Magnetostriction
b) Vibrating diaphragm
c) Moving coil
d) Oscillating coil

In a constant power type load
a) Torque is proportional to speed b) Torque is proportional to square of speed
c) Torque is inversely proportional to speed
d) Torque is independent or speed.

The frame of an induction motor is usually made of.......
a) Silicon steel b) Cast iron
c) Aluminicun d) Copper

Slip rings arc usually made of......
a) Copper
b) Carbon
c) Phosphor bronze
d) Aluminium

In a hydro-electric plant a conduct system for taking  water from the intake works to the turbine is known as.....
a) Dam  b) Reservoir
c) Penstock d) Surge tank

The shaft of an induction motor is made from.........
a) High speed steel
b) Stainless steel
c) Carbon steel
d) Cast iron

In a induction motor, no-load slip is generally.........
a) Less than I percent b) 5 percent
c) 2percent d) 4 percent

The most common type of ac motor is the.........
a) Single phase induction motor b) Two-phase induction motor
c) Three-phasc induction motor
d) Two-phase squirrel-cage motor

A single-phase induction motor ...........
a) Is self-starting
b) Operates at a fixed speed
c) Is less reliable than a three-phase synchronous motor
d) None of the above