VOCATIONAL TEACHER - MAINTENANCE AND REPAIRS OF RADIO AND TELEVISION.pdf (Size: 1.51 MB / Downloads: 0)

1.The distribution of electrons in the conduction band is given by :
(A)(density of quantum states ) x (energy of a state)
(B)(density of quantum states) x (probability a state is occupied)
(C )(energy of quantum states) x (probability a state is occupied)
(D)(energy of quantum states) x (chemical potential of a state)

2.Temperature coefficient of diode at room temperature is
(A)-1.22 mV/° C(B) -1.42 mV/° C
(C ) —1.62 mV/°  C(D) -1.82 mV/°  C

3.When the reverse bias increases for a diode, the PN junction capacitance :
(A)Increases, exhibiting.inverse square relation
(B)Decreases, exhibiting inverse square relation
(C )Decreases, exhibiting inverse square root relation
(D)Increases, exhibiting inverse square root relation

4.Consider an ideal intrinsic semiconductor in thermal equilibrium. No external forces or fields are applied to this semiconductor. At temperatures above 0 K, the electron concentration in the conduction band is non-zero because :
(A)some electrons from dopant atoms will overcome the bnndgap by gained thermal energy
(B)some electrons from the conduction band will overcome the bandgap by gained thermal energy
(C )some electrons from dopant atoms will overcome the ionization energy by gained thermal energy
(D) some electrons from the* valence band will overcome the bandgap by gained thermal energy .

5.A junction FET has the following parameters. Ioss= 20 mA, Pinch off voltage = 5V. The gate source cut off voltage is : •
(A)-5V(B)5 V
(C )10 V(D)-10 V

6.The capacitance in parallel with forward biased base emitter terminals of a transistor is known as:
(A)Depletion Capacitance(B)Drift Capacitance
(C )Diffusion Capacitance(D)DopingCapacitance

7.Due to Early effect, for a transistor :
(A)Output resistance increases (C ) Input resistance decreases
(B)Input resistance increases (D) Output resistance decreases

8.In a MOSFET, the drain current slightly Increases as the drain source voltage increases. The phenomenon is known as :
(A)Hot electron effect(B) Channel length Modulation
(C )Base width modulation(D) Sub threshold conduction

9.A MOSFET has a channel length lpum. What value of Vds will cause the electrons to reach saturation velocity :
(A)1V'(B)5 V
(C )10 V(D)15 V

10.In the devices given below, maximum switching speed is available with :
(A)SCR(B)POWERMOSFET
(C )IGBT(D)DLAC

11.The voltage gain for a differential amplifier, with the following specification A= 100, Ruj = 100K Ω , Ro= 100 Ω, Ro= 10K Ω and RL = 1,000 Ω :
(A)19.15 dB(B)38.3 dB
(C )57.45 dB(D)76.6 dB

12.The intrinsic voltage gain, pu of the BJT is :
(A)gm*ro
(C ) g<l-r„)
(B)+ M
(D) gm(r0/a-O

13.If ground is applied to the (+) terminal of an inverting op-amp, the (-) terminal will
(A)not need an input resistor(B) be virtual ground'
(C ) have high reverse current(D) not invert the signal

14.Terminal current gain for the common emitter amplifier is :
(A)ratio of Collector current to Base current
(B)ratio of current delivered to load to current supplied to base
(C )β of the transistor
(D)all the above

15.Negative feedback in transistor amplifier has the advantage of:
(A)Extendedbandwidth(B)Improvedloopgain
(C )Increasedharmonic distortion(D)All the abovej

16.The feedback in an amplifier circuit reduces the gain to 50%. The feedback factor is :
(A)-1.5 dB(B)-0.5 (IB
(C )-3 dB(D)1.5 dB

17.For an LC tuned circuit, :
(A)When the capacitor energy is maximum, the inductor energy is minimum
(B)When the capacitor current is maximum, the inductor current is minimum
(C )When the capacitor voltage is maximum, the inductor voltage is minimum
(D)When the capacitor voltage is maximum, the inductor energy is minimum

18.Fastest of all logic families :
(A) Emitter coupled logic (C ) CMOS logic
(B)Resistor Transistor logic
(D)Transistor - Transistor logic

19.AD 670 is a :
(A) Successive approximation ADC (C ) Counter ramp ADC
(B)Dual slope ADC (D) Flash ADC

20. Noise due to random emission of electrons associated barrier is known as :
(A) Thermal Noise (C ) Cosmic Noise
(B)White Noise
(D)Shot Noise

21.A broadcast radio transmitter radiates 5 kW power when the modulation percentage is 60%. The carrier power is :
(A) 1.19 kW(B) 3.12 kW
(C )4.23 KW(D) 6.46 kW

22.The advantage of DSB over SSB full carrier AM is :
(A)1/588 available channel space
(B) More stable transmitter gives better reception
(C )More power to transmit same signal
(D)Signal is less resistant to noise

23.Double aide band modulator is used to obtain :
(A)Double side band suppressed carrier signal (B) Single side band suppressed carrier signal (C ) Double side band signal
(D)Single side band signal

24.VSB modulation is preferred in TV because :
.(A) it avoids phase distortion at low frequencies
(B)it reduces the bandwidth requirement to half
(C )it results in better reception
(D)all the above

25.Which of the following is the indirect way of FM generation?
(A)Reactance bipolar transistor modulator (B) Armstrong modulator
(C )Varactor diode modulator
(D)Reactance FM modulator

26.An FM signal with a deviation 3 is passed through a mixer and has its frequency reduced to half. The deviation in the output of the mixture is :
(A)ð/2(B)23
(C )3/4(D)3

27.A 1000 kHz carrier is simultaneously modulated with 300 Hz, 800 Hz and 2 kHz audio sine waves. Which of the following frequency is least likely to be present in the output?
(A)1002 kHz(B)1000 kHz
(C )999.2 kHz(D)998.0 kHz

28.In the spectrum of a FM wave :
(A)The carrier frequency disappears when the modulation index is large
(B)The amplitude of any side band depends upon the modulation index
(C )The total number of side band depends upon modulation index
(D)The number of side bands increase with increase in modulation frequency

29.Amplitude limiting action is achieved in :
(A)Foster-Seely discriminator(B)Quadrature Detector
(C ) PLL demodulator *(D) Ratio detector

30. Consider the following :
1.Generation of SSB signals
2.Design of minimum phase type filters
3.Representation of band pass signals

31.Which of the above applications is Hilbert transform used?
(A)1 only(B)1,2 and 3
(C )1,2 only(D)1 and 3

32.Main disadvantage of PCM is :
(A)It needs large bandwidth(B)It is incompatible with FDM
(C )High error rateHigh error rate(D)In compatible with time sharing
 
32. In phase shift keying the input signal is
(A)(0 = A cos o)al and s2(0 = -A cos
(B)(t) = s2 (/) - A cos (oQl
(C )s* (/) = A cos a)0t. and s2 (t) = A cos(<y0< + */ 2)
(D)= A coso0{i) and s2(f) = -A cos(o0t \ n!2)

33.Rather than sending the absolute value of each sample, it is possible to achieve a smaller transmission bit-rate by sending the difference between consecutive samples. This is known as:
(A)delta-sigma modulation(B) delta modulation
(C ) adaptive delta modulation(D) differential PCM

34.The impulse response of a linear interpolator is :
(A) A square pulse(B) Rectangular pulse
(C ) Linear ramp(D) Triangular pulse

35.Compandor, in digital communication refers to :
(A) Compressor(B) Expander
(C ). Both (A) and (B) (D) None of the above

36. Slotted frequency hopping is :
(A) Synchronous frequency hopping (C ) Random frequency hopping
(B) Sequential frequency hopping (D) Asynchronous frequency hopping

37.Bit length of a pseudo noise code, having m stage shift register is : 
(A) 2m(B) 2m~1
(C ) 2m -1(D) 2"-1

38.The rate of change at the output of the modulator is :
(A)Bit rate(B) Baud rate
(C ) Deviation rate(D) Pulse rate

39.What is false for a Frequency Hopping Spread spectrum?
(A)It is not affected by near far problem
(B)It is affected by near far problem
(C )It. has multiple frequency bands
(D)The carrier frequency randomly changes among different slots

40.The ratio of the bandwidth of spreaded signal to the bandwidth of the unspreaded signal is termed as:
(A)Band rejection ratio(B)Band width factor
(C )Processing gainCD)Processing factor

41.In a broadcast superheterodyne receiver having no KF amplifier, the loaded Q of the antenna coupling circuit is 100. If the intermediate frequency is 455 kHz. The rejection ratio at 25 MHz will be :
(A)1.116.(B)1.386
(C )2.116(D)2.386

42.Most antenna consisting of a 50 meter long vertical conductor operates over a perfectly conducting ground plane. It is base fed at a frequency of 600 kHz. The radiation resistance of the antenna in ohms is :
(A)2jt2 5(B)5
(C )i£l(D)20л220/r

43.Diffraction of electromagnetic waves :
(A)is caused by reflections from the ground
(B)arises only with spherical wavefronts
(C )will occur when the wave pass through a large slot
(D)will occur around the edge of a sharp obstacle

44.The filter which provides full luminance bandwidth without destroying precious high frequency information :•
(A) Trap filter   •(B)Comb filter
(C ) Chroma Filter(D)Luma Filter

45. While dots and cross latch patterns are called : 
(A) Divergence patterns (C ) Linear patterns
(B) Convergence patterns (D) Back ground patterns

46. Magnitude of the signal formed by Q and I represents :
(A)Hue
(C )
Hue
Contrast

47. JPEG 2000 standard uses :
(A) DCT transformation (C ) Wavelet transformation

Which of the following statement in incorrect with watchdog control register,when an external RESET is applied:
(B) Brightness (D) Color Saturation
(B) Hilbert transformation (D) DST transformation

48.The dispersion is caused by the shape and index profile of the fibre core is :
(A) Waveguide dispersion(B) Modal dispersion
(C )Chromatic dispersion(D)Material dispersion

49.Numerical Aperture for a multimode fiber is in the range of:
(A)0 to 0.1(B)0.1 to 0.2
(C )0.2 to 0.3(D)0.3 to 0.4

50.Noise caused by reflections returning a portion of the optical signal back into the laser cavity is termed as :
(A)Relative Intensity noise(B)Phase noise
(C )Drift(D)Intercavity noise

51.The I/O port that does not have a dual-purpose role is :
(A) Port 3 (C ) Port 1
(B) Port 2 (D) Port 0

52.After reset, SP register is initialized to address :
(A) 6H. (B) 7H
(C )8H(D)9H

53.Which ofthe following statement is incorrect withwatchdogcontrol register,when an external RESET is applied :
(A)Watchdog run bit is act to OFF(B)Watchdogrun bit is set to ON
(C )Watch dog time out flag is cleared(D)Auto loadtakes place

54.When 8051 Microcontroller is interfaced with RS 232 :
(A)No extra hardware needed for connection
(B)Current Buffer is connected in between
(C )Line converter is connected in between
(D)V to F converter is connected in between

55.Select the correct statement for 8051 hardware :
(A)CPU8Bit, PC 16 Bit,DPTR 8 bit, PSW 16 Bit, SP 16 Bit
(B)CPU8Bit, PC 8 Bit, DPTR 16 bit, PSW 16 Bit, SP 8 Bit
(C )CPU8Bit, PC 16 Bit,DPTR 8 bit, PSW 8 Bit, SP 16 Bit
(D)CPU8Bit, PC 16 Bit,DPTR 16 bit, PSW 8 Bit, SP 8 Bit

56.With the help of RISC Architecture, P1C16F887 Microcontroller has reduced instruction set. Number of instructions that CPU can recogonize is :
(A) 25(B)35
(C ) 45(D)5555

57.The ADC0804 has__________resolution (A) 32 bitresolution.(B).16 bit
(C ) 8 bit(D)4 bit4 bit

58.An alternate function of port pin P3.0 (RXD) in the 8051 is :
(A)serial port input(B)serial port output
(C )memory write strobe(D)memory read strobe

59.-----------can monitor everything that goes in on-board CPU gives complete visibility into
the target code’s operation.
(A)Debugger(B)Simulator
(C )In Circuit Simulator(D)Logic Analyser

60.ARM Processor Cortex A8,processor mode IRQ refers to
(A)General purpose interrupt handling
(B)Fast interrupt handling
(C )A secure mode for TrustZone
(D)A protected mode for the Operating System

61.N point DFT of the sequence ð(n) is :
(A)(B)
(C )•£">>"'”‘=i.(D)

62.If x(n) is having DFT X(K), then the DFT of x(N-n) is :
(A) X(K-N)(B) X(N-K)
(C ) (X (K-N))/N•(D) (X(N-K))tN

63.21 tap linear-phase FIR filter operating at a 1 kHz rate has delay :
(A) 2 ms((B) 4 ms
(C ) 8 ms(D) 10 ms

64.Resampling is usually done :
(A)If sampling frequency is less than Nyquist frequency
(B)If sampling frequency is equal to Nyquist frequency
(C )To interface two systems which have equal sampling rates
(D)To interface two systems which have different sampling rates

65.Scaling in a digital filter is needed to :
(A) Avoid overflow(13) Avoid noise due to round off errors
(C ) Both (A) and (B)(D) None of the above

66.The TMS320C6713 processor supports--------prioritized interrupts.
(A) 8(B)12
(C ) 16(D) 20

67.In TDM to RDM conversion, the operation needed are :
(A)Correlation and filtering(B)Correlation and interpolation
(C )Interpolation and correlation(D)Interpolation and modulation

68.For an FIR filter design, pass hand lower frequency is :
(A)Zero(B)Half the output rate
(C )Half the passband upper frequency(D)None of the above

69.Which is not a disadvantage of IIR filter?
(A) They are more susceptible to problems of finite-length arithmetic
(B)They are harder (slower) to implement using fixed-point arithmetic
(C )They don’t offer the computational advantages of FIR filters
(D)They can’t achieve a given filtering characteristic using less memory

70.For 8051 Micro controller ORG is used to :
(A)Do the logic OR operation(B)Offset Register with a byte
(C )Define address(D)Clearing Odd flag register

71.PWM switching is preferred in voltage source inverters for the purpose of:
(A) Controlling output voltage(B) Reducing filter size
(C ) All the above(D) None of the above

72.For a given torque, increasing diverter- resistance of a dc series motor :
(A)Decreases its speed, but armature current remains the same
(B)Decreases its speed, reducing armature current
(C )Increases its speed, reducing armature current
(D)Increases its speed, but armature current remains the same

73.Triac can be used in :
(A) ac voltage regulator (C ) cycloconverter
(B) inverter
(D) solid state type of devices

74.A boost regulator has an input voltage of 5V and average output voltage of 15V. The duty cycle is:
(A)2/3(B)1/3
(C )5/2(D)15/2

75.Stepper motors are mostly used for :
(A) high power requirements(B) control system applications
(C ) very high speed of operation(D) very low speed of operation

76.The most suitable device for high frequency inversion in SMPS is :
(A)BJT(B)1GBT
(C )MOSFET(D)GTO

77.In a self-controlled synchronous motor fed from a variable frequency converter :
(A)The rotor poles invariably have damper winding
(B)The frequency of stator decides the rotor speed
(C )There arestartingproblems
(D)The speedof rotordecides rotor frequency

78.An ideal chopper operating at a frequency of 500 Hz supplies a load having a resistance of 3 Ω and an inductance of 9mH from a 50 V battery. The mean value of load voltage for on/off ratio of 4/1 is :
(A) 200 V(B) 25 V
(C ) 4 V(D) 40 V

79.The most suitable solid state converter for controlling the speed of three- phase cage motor at 25 Hz is:
(A) Cycloconverter(B) Current source inverter
(C ) Voltage source inverter(D) Load commutated inverter

80.A four quadrant chopper cannot be operated as :
(A)One quadrant chopper(B)Cycloconverter
(C ) Inverter(I)) Bi-directional rectifier

81.Who started n magazine called “Sivayoga Vilasam"?
(A)Brahmananda Sivayogi(B)Vagbhatananda
(C )T.K. Madhavan(D)A.K. Gopalan

82.The first annual .session of the SNDP having been held at:
(A)Aruvippuram(B)Kollam
(C )Chempazhanthi(D)Kochi

83.The headquarters of the Kerala Press Acadamy :
(A) Thiruvananthapuram(B) Thrissur
(C ) Kozhikodu(D) Kochi

84.Who was the first women High court Judge in all over India?
(A) Meera kumar(B) Fatima Beevi
(C ) Anna Malhothra(D) Annachandi

85.Who was known as “Sarva Vidyadi Rajon"?
(A) Sree Narayana Guru (B) Kumaranasan
(C ) Chattampi Swamikal(D) K. Kelappan

86.The first person to get Dadasaheb Phalke Award from Kerala :
(A)Adoor Gopala Krishnan(B)Premji
(C )Shaji N. Karun(D)P.J. Antony

87.Which one of the following was not the work of Ur. A.P.J. Abdulkalam?
(A)Agnichirakukal
(B)Indomitable spirit
(C )Images and insight
(D)India - 2020 A vision for New Milleniyam

88.Malayali memorial was submitted to the maharaja of travancore on :
(A)June 1, 1891(B)January 1, 1891
(C )July 10, 1890(D)January 10, 1890

89.The present form of Kathakali was designed by :
(A)Vallathol
(B)Unnayi Variyar
(C )Kottayam tampuran
(D)Kodungallur Kunhikkuttan Thampuran

90.Who called Ayyankali “Pulaya Raja”? (A) Gandhi (C ) Ambedkar
(B) Sree Narayana Guru (D) Dr. Palpu

91."Athmakathakku Oru Amukham” is the autobiography of:
(A)Lalitha prabhu(B)Arya pallam
(C )Lalithamhika Antharjanam(D)Thakazhi

92.Name the first state in India to install earth quake early warning system : 
(A) Delhi(B) Uttarakhand
(C ) Manipur(D) Maharashtra

93.Vala samudaya Parishkarani sabha was started by :
(A)Sahodaran Ayyappan(B)K. Kelappan
(C )K.P. Karuppan(D)Ayyankali

94.Which state introduced compulsory voting in local Governments elections? 
(A)Gujarath(B)Rajastan
(C )Kerala(D)Tamil Nadu

95.Uniform Civil Code was contained in which article : (A)Article 14(B)
(C ) Article 24i (D)Article 41 Articel 44

96.Which programme aims to achieve slum free India? 
(A)Indira Awas Yogana(B)
(C )Roshtriya Swasthya Bhim Yogana
(D)Jan Dhan Yogana Rajiv Awas Yogana

97.Which of the following is the famous novel of S.K. Pottekkadu?
(A) Visha Kanyaka(B) Nellu
(C ) Pandavapuram(D) Marana certificate

98.The preamble to our constitution includes all except:
(A) Fraternity(B) Adult franchise
(C ) Equality of status(D) Justice

99. Who was known as “Sarasa druda kavi kireeda mani”?
(A) Kerala varma valiya koyi tampuran (B) 
(C ) Chandu menon(D)Kodungallur Kunhikkuttan Tampuran

100. India accepted the idea of Judicial Review from :
(A) Britain•(B)USA
(C ) Australia(D)Canada