UGC NET Electronics Science Exam - December 2005 : Quiz & Solutions

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Test your Preparation by solving UGC - NET 2005 (Electronics Science) Exam Question Paper :

1. The threshold voltage of an n-channel MOSFET can be increased by :
a. increasing the channel dopoint concentration
b. decreasing the channel dopoint concentration
c. reducing the gate oxide thickness
d. reducing the channel length

2. The potential difference between two points can be expressed as :
a. Volt per meter
b. Watt per ampere
c. Coulomb per Newton
d. Volt per ampere

3. Laplace tarnsform of is :
a.
b.
c.
d.

4. In a linear network the ratio of voltage excitation to current response is unaltered when position of excitation and response are interchanged. This assertion stems from :
a. principle of duality
b. principle of superposition
c. reciprocity theorem
d. equivalent theorem

5. The bandwidth of an amplifier can be increased by :
a. decreasing the capacitance of its bypass filter
b. increasing input signal frequency
c. cascading it
d. minimising its stray capacitance

6. Without the DC source, a clipper acts like a :
a. rectifier
b. clamper
c. demodulator
d. chopper

7. In order to build a mod-6 counter using three flip-flops the number of possible count sequence is :
a. 4
b. 8
c. 16
d. 28

8. The content of a 4-bit register is 1101. The register is shifted 6 times to the right with serial input being 101101. The final content of the register will be :
a. 1011
b. 0010
c. 1010
d. 0111

9. A microprocessor with a 16-bit address bus is used in linear memory selection configuration with 4 memory chips, the maximum addressable memory space is :
a. 64 k
b. 16 k
c. 8 k
d. 4 k

10. The interface chip used for data transmission between 8086 and 16 bit ADC is :
a. 8259
b. 8255
c. 8253
d. 8251

11. The FORTRAN statement A52.5, J55*A22**4/2 will calculate J as :
a. 12
b. 8.5
c. 4.5
d. 4

12. A pointer is a variable that contains as its value :
a. the dimension of another variable
b. the address of another variable
c. the size of another variable
d. the value of another variable

13. An electromagnetic wave travels in free space with electric field component . Its angular frequency w is :
a. 3e8 m/s
b. 3e8 rad/s
c. 1.5e8 rad/s
d. 1e8 rad/s

14. The behaviour of which of the following devices is governed by bulk effect :
a. Gunn diode
b. PIN diode
c. Tunnel diode
d. IMPATT diode

15. A frequency modulated signal is expressed as :
a. A cos [ wct1 K m(t) ]
b. A cos [ wct 1ϕ ]
c. A cos [ wct ]
d. A cos [ wct1K ∫m(λ) dλ ]

16. In PCM system if the quantisation levels are increased from 2 to 8, the relative bandwidth requirement will :
a. become four times
b. remain same
c. be tripled
d. be doubled

17. Optical communication systems generally use :
a. amplitude modulation
b. frequency modulation
c. phase modulation
d. intensity modulation

18. A device that exhibits a negative resistance region is :
a. P-N diode
b. UJT
c. JFET
d. BJT

19. A pyrometer is used to measure :
a. temperature
b. pressure
c. light intensity
d. low current

20. A linear discrete-time system has the characteristic equation . The system :
a. is stable
b. is marginally stable
c. is unstable
d. assessed

21. Assertion (A): At high temperature, the avalanche breakdown voltage is higher. Reason (R): At higher temperature mean free paths of electrons and holes are shorter, therefore a larger field is required to cause ionisation.
a. Both (A) and (R) true and (R) is the correct explanation of (A)
b. Both (A) and (R) true but (R) is not the correct explanation of (A)
c. (A) is true but (R) is false
d. (A) is false but (R) is true

22. Assertion (A): The Wien Bridge can be used for frequency measurements. Reason (R): The Wien Bridge uses only capacitors and resistors.
a. Both (A) and (R) true and (R) is the correct explanation of (A)
b. Both (A) and (R) true but (R) is not the correct explanation of (A)
c. (A) is true but (R) is false
d. (A) is false but (R) is true

23. Assertion (A): A demultiplexer cannot be used as a decoder. Reason (R):A demultiplexer is built using AND gates only.
a. Both (A) and (R) true and (R) is the correct explanation of (A)
b. Both (A) and (R) true but (R) is not the correct explanation of (A)
c. (A) is true but (R) is false
d. (A) is false but (R) is true

24. Assertion (A): In Intel 8085, the lower byte of address and data are multiplexed. Reason (R): This helps limit the number of external pin terminals.
a. Both (A) and (R) true and (R) is the correct explanation of (A)
b. Both (A) and (R) true but (R) is not the correct explanation of (A)
c. (A) is true but (R) is false
d. (A) is false but (R) is true

25. Assertion (A): The solution of Poisson equation is the same as the solution of Laplace equation. Reason (R): The Laplace equation is the same as Poisson equation for source free region.
a. Both (A) and (R) true and (R) is the correct explanation of (A)
b. Both (A) and (R) true but (R) is not the correct explanation of (A)
c. (A) is true but (R) is false
d. (A) is false but (R) is true

26. Assertion (A): The total emf induced in a circuit equals the time rate of change of the total magnetic flux linking the circuit. Reason (R): The induced current in a loop is always so directed as to produce a flux opposing the change in the flux density.
a. Both (A) and (R) true and (R) is the correct explanation of (A)
b. Both (A) and (R) true but (R) is not the correct explanation of (A)
c. (A) is true but (R) is false
d. (A) is false but (R) is true

27. Assertion (A): AM has better noise performance than FM. Reason (R): AM results in increase in signal power.
a. Both (A) and (R) true and (R) is the correct explanation of (A)
b. Both (A) and (R) true but (R) is not the correct explanation of (A)
c. (A) is true but (R) is false
d. (A) is false but (R) is true

28. Assertion (A): Optical communication has shifted from 1.3 mm to 1.55 mm in silica fibers. Reason (R): Dispersion and attenuation are both minimum at 1.55 mm.
a. Both (A) and (R) true and (R) is the correct explanation of (A)
b. Both (A) and (R) true but (R) is not the correct explanation of (A)
c. (A) is true but (R) is false
d. (A) is false but (R) is true

29. Assertion (A): Thyristors are preferred to power diodes in variable power rectifiers. Reason (R): Thyristors provide controlled rectification and also power loss in them is less compared to that in power diodes.
a. Both (A) and (R) true and (R) is the correct explanation of (A)
b. Both (A) and (R) true but (R) is not the correct explanation of (A)
c. (A) is true but (R) is false
d. (A) is false but (R) is true

30. Assertion (A): An important property of laser radiation is its coherence. Reason (R): Stimulated emission is the key to the operation of LASER.
a. Both (A) and (R) true and (R) is the correct explanation of (A)
b. Both (A) and (R) true but (R) is not the correct explanation of (A)
c. (A) is true but (R) is false
d. (A) is false but (R) is true

31. Consider the following semiconductor diodes : 1. Germanium diode 2. Silicon diode 3. Tunnel diode 4. Schottky diode The correct increasing order of forward voltage drop of the above diodes is :
a. 1, 3, 4, 2
b. 1, 2, 3, 4
c. 3, 4, 2, 1
d. 3, 1, 4, 2

32. In the microwave region some of the band designations are Ku, X, K and Ka. The order according to their allocated frequency band is :
a. Ku, X, K, Ka
b. X, Ku, K, Ka
c. Ka, Ku, K, X
d. K, X, Ku, Ka

33. Consider the Analog to Digital converters given below : 1. Successive approximation ADC 2. Dual Ramp ADC 3. Counter method ADC 4. Simultaneous ADC The correct sequence of the ascending order in terms of conversion times of the above ADC’s is
a. 3, 2, 4, 1
b. 2, 3, 4, 1
c. 2, 3, 1, 4
d. 3, 2, 1, 4

34. The various subsystems in an FM receiver are arranged as : 1. Mixer, RF amplifier, limiter, IF amplifier, discriminator, audio amplifier 2. RF amplifier, mixer, IF amplifier, limiter, discriminator, audio amplifier 3. RF amplifier, mixer, limiter, discriminator, IF amplifier, audio amplifier 4. Mixer, IF amplifier, limiter, audio amplifier, discriminator, RF amplifier The correct sequence of subsystems is :
a. 1
b. 2
c. 3
d. 4

35. Four main types of telephone exchanges available in India are : 1. Manual 2. Electronic 3. Strowger 4. Cross-bar The correct order in which they appeared in our country is :
a. 1, 2, 3, 4
b. 2, 1, 4, 3
c. 1, 3, 4, 2
d. 1, 4, 3, 2

36. Match the List-I with List-II :

        List-I                      List-II
    (a) BJT                       (i)   Negative resistance
    (b) MOSFET                    (ii)  High current gain
    (c) Tunnel Diode              (iii) voltage regulation
    (d) Zener Diode               (iv)  High input impedence

a. (i)(ii)(iii)(iv)
b. (ii)(iv)(i)(iii)
c. (iv)(iii)(ii)(i)
d. (iii)(i)(ii)(iv)

37. Match the List-I with List-II :

        List-I                      List-II
    (a) Linearity                 (i)   Superposition theorem
    (b) Structure                 (ii)  Norton's theorem
    (c) Equivalent circuit        (iii) Tellegen's theorem
    (d) Bilateral                 (iv)  Reciprocal theorem

a. (iii)(ii)(iv)(i)
b. (iv)(i)(ii)(iii)
c. (i)(ii)(iii)(iv)
d. (i)(iii)(ii)(iv)

38. Match the List-I with List-II :

        List-I                      List-II
    (a) Wein bridge               (i)   RF Oscillator: 2 inductance and 1 capacitance
    (b) Colpitt                   (ii)  LC Oscillator for RF: 3 capacitance and 1 inducatnce
    (c) Hartley                   (iii) RC Oscillator for audio frequecy
    (d) Clapp                     (iv)  RF Oscillator: 2 capacitor and 1 inductance

a. (i)(ii)(iii)(iv)
b. (iv)(iii)(ii)(i)
c. (ii)(iii)(iv)(i)
d. (iii)(iv)(i)(ii)

39. Match the List-I with List-II :

        List-I                      List-II
    (a) Multiplexer               (i)   Sequential memory
    (b) Demultiplexer             (ii)  Converts decimal to binary
    (c) Shift Register            (iii) Data selector
    (d) Encoder                   (iv)  Routes out many output with single input

a. (i)(ii)(iii)(iv)
b. (iv)(iii)(ii)(i)
c. (iii)(iv)(i)(ii)
d. (ii)(i)(iv)(iii)

40. Match the List-I with List-II :

        List-I                      List-II
    (a) Sign flag                 (i)   7th bit
    (b) Zero flag                 (ii)  8th bit
    (c) Parity flag               (iii) 1 bit
    (d) Carry fla                 (iv)  3rd bit

a. (ii)(i)(iv)(iii)
b. (i)(ii)(iii)(iv)
c. (iv)(ii)(i)(iii)
d. (iii)(iv)(i)(ii)

41. Match the List-I with List-II :

        List-I                      List-II
    (a) Pointer                   (i)   C Program
    (b) Dimension                 (ii)  Array
    (c) Header                    (iii) Real variable
    (d) FLOAT                     (iv)  Memory address

a. (i)(ii)(iii)(iv)
b. (iv)(ii)(i)(iii)
c. (iii)(iv)(i)(ii)
d. (ii)(i)(iv)(iii)

42. Match the List-I with List-II :

        List-I                      List-II
    (a)                     (i)   Gauss' law for electric field
    (b)                     (ii)  Ampere's law
    (c)                     (iii) Faraday's law
    (d)                     (iv)  Gauss' law for magnetic field

a. (i)(ii)(iii)(iv)
b. (iv)(i)(iii)(ii)
c. (iii)(iv)(ii)(i)
d. (ii)(iii)(i)(iv)

43. Match the List-I with List-II :

        List-I                      List-II
    (a) AM Broadcast              (i)   Multipath phenomenon
    (b) FM Broadcast              (ii)  535 - 1600 KHz
    (c) TV Broadcast              (iii) VSB modulation
    (d) Point to Point            (iv)  88 - 108 MHz

a. (i)(ii)(iii)(iv)
b. (iii)(iv)(ii)(i)
c. (ii)(iv)(iii)(i)
d. (i)(iii)(iv)(ii)

44. Match the List-I with List-II :

        List-I                      List-II
    (a) LDVT                      (i)   Pressure
    (b) Bourdon gauge             (ii)  Temperature
    (c) Strain gauge              (iii) Displacement
    (d) Thermister                (iv)  Stress

a. (i)(ii)(iii)(iv)
b. (iii)(i)(iv)(ii)
c. (iv)(i)(iii)(ii)
d. (ii)(i)(iv)(iii)

45. Match the List-I with List-II :

        List-I                      List-II
    (a) Polarisation              (i)   Bandwidth
    (b) Coherence                 (ii)  LCD
    (c) Total internal reflection (iii) Laser
    (d) Dispersion                (iv)  Optical fiber

a. (ii)(iii)(iv)(i)
b. (i)(ii)(iii)(iv)
c. (iv)(iii)(ii)(i)
d. (ii)(i)(iii)(iv)

Linked Items

[Read the passage below and answer the questions that follow based on your understanding of the passage] In 1990 Planck proposed, in order to explain the distribution of energy in the spectrum of black body, that an oscillating electron may not radiate or absorb energy continuously, as required by classic electrodynamics, but only in integer multiples of a fundamental unit called quantum. If f is the frequency of radiation, the energy of a quantum is given by E = hv where h is a constant known as Planck's constant. In 1905, Einstine went further and suggested that light, or electromagnetic radiation in general, might sometimes be regarded having a corpuscular or particle like nature. The light particles, or quanta, are called photons. Photons are peculiar in that they travel with the speed of light and have zero rest mass. What is important to notice is that can be thought of either as waves with particle like properties or as particles with wave like properties. In 1924 de Broglie generalised the idea and suggested that any moving particles with mass m and speed v, will in some experiments display wave like properties with wavelength = h/mv.

46. A quantum of visible light is called :
a. Photon
b. Proton
c. Hyperon
d. Phonon

47. A quantum will have more energy if :
a. the wavelength is longer
b. the frequency is higher
c. the amplitude is higher
d. the velocity is greater

48. The photon has its velocity in vacuum equal to :
a. 3e9 cm/s
b. 3e10 cm/s
c. 3e10 km/s
d. 9e10 cm/s

49. For an electron moving with a speed of 5.9e8 cm/sec, the accompanying wave will have a wavelength of :
a. 1.2e-8 cm
b. 1.2e-10 cm
c. 1.2e-6 cm
d. 1.2e-12 cm

50. The electron microscope works on the basis of :
a. refraction of light in lenses
b. wave like properties of electron in motion
c. pressure exerted by electron beam
d. Production of electromagnetic wave by impact of electrons on matter.

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