IES 2009 E & T Solved Question paper 1 Objective

1. Which of the following statements is/are true for the diamond structure?
i. Coordination number is four

ii. Packing fraction is 0.34

iii. Copper crystallizes into diamond structure

iv. Lattice is FCC

Select the correct answer using the codes given below:

a) i only

b) i,ii and iv

c) ii and iii only

d) ii, iii and iv

Ans: Option b)

2. Which of the following statements is/are true for a good conductor of electricity?

i. Its conductivity decreases with increasing temperature

ii. Number of free electrons is around 10²⁶ m^-3

iii. Its conductivity decreases with addition of impurities

iv. It is a good conductor of heat also

Select the correct answer using the codes given below:

a) i, ii, iii and iv

b) i only

c) ii and iii only

d) iii and iv only

Ans: Option a)

3. Which of the following materials is not an insulator?

a) Diamond

b) Graphite

c) Bakelite

d) Lucite

Ans: Option b)

4. Consider the following statements:

The conductivity of a metal has negative temperature coefficient since:

i. The electron concentration increases with temperature

ii. The electron mobility decreases with temperature

iii. The electron-lattice scattering rate increases with temperature.

Which of the above statements is/are correct?

a) i only

b) i and ii 

c) ii and iii

d) iii only

Ans: Option c)

5. Which of the following is not conducting material?

a) Copper

b) Tungsten

c) Germanium

d) Platinum

Ans: Option c)

6. What is the chemical bonding in silicon semiconductor?

a) Metallic

b) Ionic

c) Covalent

d) Van der Waals

Ans: Option c)

7. Which of the following is a trivalent material? 

a) Antimony

b) Phosphorous

c) Arsenic

d) Boron

Ans: Option d)

8. The fuse material used in electrical lines must have which one of the following properties?

a) High resistivity

b) Low conductivity

c) High melting point

d) Low melting point

Ans: Option d)

9. Manganin, an alloy of copper and manganese is used in

a) Soldering material

b) Heating elements

c) Ballast resistors

d) Standard resistances

Ans: Option d)

10. Which if the following pairs is not correctly matched?

a) NaCl         Diamagnetic

b) Gd            Paramagnetic

c) Ferrite       Ferrimagnetic

d) Cr2O3      Ferromagnetic

Ans: Option b)

11. Hysteresis loss in a transformer working at 220 V and at frequency of 50 Hz is 100 W. When the transformer is operated at 220 V and at a frequency of 100 Hz, What is the hysteresis loss?

a) 50 W

b)100 W

c) 200 W

d) 400 W

Ans: Option c)

12. Which of the following is not an electro-magnetic device?

a) Hall Transducer

b) Transformer

c) Speedometer

d) Eddy current damping device

Ans: Option a)

13. Which one of the following materials is used for making permanent magnets?

a) Steel

b) Carbon

c) Carbon-Steel

d) Graphite

Ans: Option c)

14. What happens when a paramagnetic material is heated above Curie temperature?

a) It becomes diamagnetic

b) It becomes non-magnetic

c) It becomes ferromagnetic

d) It becomes anti-ferromagnetic

Ans: Option a)

15. Ferromagnetic materials show hysteresis in B-H characteristic. As the magnetic field is increased slowly from zero value, What is the first process which sets in the material to give net magnetization?

a) Growth of favorably oriented domains at the cost of other domains by reversible boundary displacements.

b) Growth of favorably oriented domains at the cost of other domains by irreversible boundary displacements.

c) Domain wall orientation

d) A combination of processes a) and c) above

Ans: Option d)

16. The following properties are associated with ferroelectric materials:

i) Its susceptibility is negative.

ii) The susceptibility is expressed as χ  = C/ (T – Tc)

Where  C is the curie temperature.

iii) It has permanent dipoles oriented randomly

Which of the above statements is/are correct?

a) i only

b) i and iii

c) ii only

d) i, ii and iii

Ans: Option c)

17. The materials not having negative temperature coefficient of resistivity are 

a) Metals

b) Semiconductors

c) Insulators

d) None of the above

Ans: Option a)

18. Consider the following:

i) Si 

ii) Ge

iii) GaAs

iv) InP

Which of the following semiconductors should be used for making highly efficient photodiodes?

a) i and iv only

b) iii and iv only

c) i, iii and iv 

d) ii, iii and iv

Ans: Option b)

19. Which of the following compounds is widely used for making ferrites?

a) FeO

b) CuO

c) MgO

d) Fe2O3

Ans: Option d)

20. Effective Q of the equivalent electric circuit of quartz crystal is of the order of 

a) 200

b) 2000

c) 20,000

d) 2,00,000

Ans: Option c)

21. In a material, the fermi-level is located between the center of the forbidden band and the conduction band. Then what is that material?

a) A p-type semiconductor

b) A n-type semiconductor

c) An intrinsic semiconductor

d) An insulator

Ans: Option b)

22. Consider the following statements:

1) Acceptor level is formed very close to the conduction band.

2) The effective mass of the free electron is same as that of a hole.

3) The magnitude of the charge of a free electron is same as that of a hole.

4) Addition of donor impurities adds holes to the semiconductor

Which of the following statements are correct?

a) 1 and 3

b) 2 and 3

c) 2 and 4

d) 3 and 4

Ans: Option b)

23. Diffusion current of holes in a semiconductor is proportional to ( with p = concentration of holes/unit volume)

a) dp/dx²

b) dp/dx

c) dp/dt

d) d²p/dx²

Ans: Option b)

24. The junction capacitance of linearly graded pn-junction (with applied voltage =  VB) is proportional to

a) V_B^1/2

b)V_B^-1/2

c) V_B^1/3

d) V_B^-1/3

Ans: Option d)

25. As per Hall effect, if any specimen carrying a current I is placed in a transverse magnetic field B, then an electric field E is induced in the specimen in the direction 

a) parallel to I

b) perpendicular to B and parallel to I

c) parallel to I and B

d) perpendicular to both I and B

Ans: Option d)

26. Which of the following quantities cannot be measured/determined using Hall effect?
a) Type of semiconductor ( p or n)
b) Mobility of charge carriers
c) Diffusion constant
d) Carrier concentration

Ans: Option c) 

27. A junction FET can be used as a voltage variable resistor
a) at pinch-off condition
b) beyond pinch-off voltage
c) well below pinch-off condition
d) for any value of V_DS

Ans: Option c)

28. The maximum power dissipation capacity of a transistor is 50 mW. If the collector emitter voltage is 10 V, what is the safe collector current that can be allowed through the transistor?
a) 5 mA
b) 2.5 mA
c) 10 mA
d) 25 mA

Ans: Option a)

29.

The above figure shows the symbol of 

a) p channel depletion MOSFET

b) p channel enhancement MOSFET

c) complementary MOSFET

d) p channel JFET

Ans: Option a)

30. Which of the following statements is correct for MOSFETs?

a) p channel MOS is easier to produce than n channel MOS

b) n channel MOS must have twice the area of p channel MOS for the same ON resistance

c) p channel MOS has faster switching action than n channel MOS

d) p channel MOS has higher packing density than n channel MOS

Ans: Option a)

31. The process of extension of a single-crystal surface by growing a film in such a way that the added atoms form a continuation of the single-crystal structure is called

a) Ion implantation

b) Chemical vapour deposition

c) Electroplating

d) Epitaxy

Ans: Option d)

32.  The maximum concentration of the element which can be dissolved in solid silicon at a given temperature is termed as 

a) Solid Solubility

b) Dissolution coefficient 

c) Solidification index

d) Concentration index

Ans: Option a)

33. Which of the following devices is used in the microprocessors?

a) JFET

b) BJT

c) MOSFET

d) CMOS

Ans: Option d)

34. In a CMOS CS amplifier, the active load is obtained by connecting a 

a) p channel current mirror circuit

b) n channel transistor

c) p channel transistor

d) BJT current mirror

Ans: Option a)

35. Which of the following is not LED material?

a) GaAs

b) GaP

c) SiC

d) SiO2

Ans: Option d)

36. The minimum energy of a photon required for intrinsic excitation is equal to

a) energy of bottom of conduction band

b) energy of top of valence band

c) forbidden gap energy

d) Fermi level

Ans: Option c)

37. Assertion (A): An unbiased p-n junction develops a built-in-potential at the junction with the n-side positive and the p-side negative

Reason (R): The p-n junction behaves as a battery and supplies current to a resistance connected across its terminals.

a) Both A and R are individually true and R is the correct explanation of A.

b) Both A and R are individually true and R is not the correct explanation of A.

c) A is true but R is false

d) A is false but R is true

Ans: Option c)

38. Assertion (A): Cut-in voltage for Germanium diode is greater than that for Silicon diode

Reason (R): Germanium diode has a higher reverse saturation current than Silicon diode.

a) Both A and R are individually true and R is the correct explanation of A.

b) Both A and R are individually true and R is not the correct explanation of A.

c) A is true but R is false

d) A is false but R is true

Ans: Option d)

39. Assertion (A): The h-parameter model of a BJT can be derived from its hybrid -π model and vice-versa.

Reason (R): The hybrid-π model has many more additional elements as compared to h-parameter model of the BJT.

a) Both A and R are individually true and R is the correct explanation of A.

b) Both A and R are individually true and R is not the correct explanation of A.

c) A is true but R is false

d) A is false but R is true

Ans: Option b)

40. Assertion (A): For same drain current rating N-channel MOSFET occupies more area than -channel MOSFET.

Reason (R): Electron mobility is much higher than hole mobility.

a) Both A and R are individually true and R is the correct explanation of A.

b) Both A and R are individually true and R is not the correct explanation of A.

c) A is true but R is false

d) A is false but R is true

Ans: Option d)

42. A signal x₁(t) and x₂(t) constitute the real and imaginary parts respectively of a complex valued signal x(t). What form of waveform does x(t) possess?
a) Real Symmetric
b) Complex symmetric
c) Asymmetric
d) Conjugate Symmetric

Ans: Option d)

43. A function of one or more variables which conveys information on the nature of physical phenomenon is called
a) Noise
b) Interference
c) System
d) Signal

Ans: Option d)

44.

Ans: Option a)

45. What is the period of the sinusoidal signal x(n) = 5 cos (0.2 π n)?
a) 10
b) 5
c) 1
d) 0

Ans: Option a)

46.

Ans: Option c)

47.

Ans: Option b)

48. Assertion (A): There are no convergence issues with the discrete-time Fourier series in general.
Reason (R): A discrete-time signal is always obtained by sampling a continuous time signal.

a) Both A and R are individually true and R is the correct explanation of A.

b) Both A and R are individually true and R is not the correct explanation of A.

c) A is true but R is false

d) A is false but R is true

Ans: Option d)

49. In the field of a charge Q at the origin, the potentials at A(2, 0, 0) and B( 1/2, 0, 0) are Va = 15 volts and Vb= 30 volts respectively. What will be the potential at C( 1, 0, 0 )?

a) 25 volts

b) 22.5 volts

c) 20 volts

d) 17.5 volts

Ans: Option b)

50. What will be the equipotential surfaces for a pair of equal and opposite line charges?

a) Spheres

b) Concentric cylinders

c) Non-concentric cylinders

d) None of the above

Ans: Option c)

51. If the potential functions V1 and V2 satisfy Laplace's equation within a closed region and assume the same values on its surface, then which of the following is correct?

a) V1 and V2 are identical

b) V1 is inversely proportional to V2

c) V1 has the same direction as V2

d) V1 has the same magnitude as V2 but has different direction

Ans: Option a)

52. By what name is the equation ∇. J = 0 frequently known?

a) Poisson's equation

b) Laplace's equation

c) Continuity equation for steady currents

d) Displacement equation

Ans: Option c)

53. Method of images is applicable to which fields?

a) Electrostatic fields only

b) Electrodynamic fields only

c) Neither electrostatic nor electrodynamic fields

d) Both electrostatic and electrodynamic fields

Ans: Option a)

54. Who developed the concept of time varying electric field producing s magnetic field?

a) Gauss

b) Faraday

c) Hertz

d) Maxwell

Ans: Option b)

55. 

Ans: Option b)

56. For plane wave propagating in free space or two conductor transmission line, what must be the relationship between the phase velocity Vp, group velocity Vg and speed of light C?

a) Vp > C >Vg

b)  Vp < C

c)  Vp = C =Vg

d)   Vp < Vg < C

Ans: Option a)

57. The reflection coefficient on a 500 m  long transmission line has a phase angle of -150 degrees. If the operating wavelength is 150 m, what will be the number of voltage maxima on the line?

a) 0

b) 3

c) 6

d) 7

Ans: Option d)

58. Consider the following statements:

For a 10 m long common power line connecting a switch to a light bulb

i. It is a distributed circuit.

ii. Time delay for propagation through it is negligible.

iii. It is in the form of a shielded coaxial cable of circular cross-section.

iv. As the intensity of the lamp varies, input impedance of this line also changes.

Which of the above statements is/are correct?

a) i only

b) i and ii

c) ii and iii

d) ii and iv

Ans: Option c)

59. With regard to a transmission line, which of the following statements is correct?

a) Any impedance repeats itself every λ/4 on the smith chart.

b) The S.W.R. = 2 circle and the magnitude of reflection coefficient = 0.5 circle coincide on the smith chart.

c) At any point on a transmission line, the current reflection coefficient is the reciprocal of the voltage reflection coefficient.

d) Matching eliminates the reflected wave between the source and the matching device location.

Ans: Option c)

60. It is required to match a 200 Ω load to a 450 Ω transmission line. To reduce the SWR along the line to 1, What must be the characteristic impedance of the quarter-wave transformer used for this purpose, if it is connected directly to the load?

a) 90 kΩ

b) 300 Ω

c) 9/4 Ω

d) 3/2 Ω

Ans: Option b)

61. The load end of a quarter wave transformer gets disconnected thereby causing an open-circuited load. What will be the input impedance of the transformer?

a) Zero

b) Infinite

c) Finite and positive

d) Finite and negative

Ans: Option a)

62. Multiple member of antennas are arranged in arrays in order to enhance what property?

a) Both directivity and bandwidth

b) Only directivity

c) Only bandwidth

d) Neither directivity nor bandwidth

Ans: Option b) 

63. Consider the following statements regarding an antenna:

1. It is a transducer.

2. Its performance is essentially frequency sensitive.

3. It is a reciprocal device. 

4. With increase in its effective aperture area, width of radiated beam increases.

Which of the above statements are correct?

a) 1,2 and 3

b) 1,2 and 4

c) 2 and 3 only

d) 1 and 4 only

Ans: Option a)

64.What is the minimum value of VSWR that may exist on a transmission line? 

a) Less than zero

b) Zero

c) One

d) 10

Ans: Option c)

65. Assertion (A): Capacitance of a solid conducting spherical body of radius 'a' is given by 4πϵ₀a in free space.

Reason (R): ∇ x H = j ϵ 𝛚E + J

a) Both A and R are true and R is the correct explanation of A

b) Both A and R are 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

Ans: Option b)

66. Assertion (A): The expression E = -∇V, Where E is the electric field and V is the potential is not valid for time varying fields.

Reason (R): The curl of a gradient is identically zero.

a) Both A and R are true and R is the correct explanation of A

b) Both A and R are 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

Ans: Option b)

67. 

a) Both A and R are true and R is the correct explanation of A

b) Both A and R are 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

Ans: Option d)

68. Assertion (A): As the length of the resonant antenna is increased, the number of lobes increases and the direction of the major lobes is closer and closer to the direction of the dipole.

Reason (R): As the length increases, the current distribution along the wire becomes more and more uniform.

a) Both A and R are true and R is the correct explanation of A

b) Both A and R are 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

Ans: Option c)

69. For a second order instrument, the optimum range of ξ(damping ratio), which gives good frequency response over a wide range of frequencies is
a) 0.5 to 0.6
b) 0.6 to 0.7
c) 0.7 to 0.8
d) 0.8 to 1.0

Ans: Option a)

70.The wheatstone bridge method of measuring resistance is ideally suited for the measurement of resistance values in the range of
a) 0.001 to 1 Ω
b) 0.1 to 100 Ω
c) 100 Ω to 10 kΩ
d)  100 kΩ to 10 MΩ

Ans: Option c)

71. What is the major cause of creeping in an energy-meter?
a) Over compensation for friction
b) Mechanical vibrations
c) Excessive voltage across the potential coil
d) Stray magnetic fields

Ans: Option a)

72. A compensated wattmeter has its reading corrected for error due to which one of the following parameters?
a) Frequency
b) Friction
c) Power consumed in current coil
d) power consumed in pressure coil

Ans: Option d)

73. Which of the following bridges is also used in an oscillator?
a) Maxwell
b) Schering
c) Hay
d) Wien

Ans: Option d)

74. Which of the following meters cannot measure a.c. quantities?
a) Thermocouple
b) Hot wire
c) P.M.M.C
d) Electrodynamometer

Ans: Option c)

75. Which of the following statements is not correct for thermistors?
a) They have negative temperature coefficient of resistance.
b) The sensing element is made of sintered ceramics, which are oxides of metals in the form of beads.
c) The variation of resistance with temperature is linear.
d) The resistance value at ambient temperature may range from 100 Ωto 100 k Ω.

Ans: Option c)

76. Which of the following devices is used at the first stage of an electronic voltmeter?
a) BJT
b) SCR
c) MOSFET
d) UJT

Ans: Option c)

77. Consider the following statements regarding sources of error in a Q-meter:
1. If a coil resistance R is connected in direct measurement mode and if the residual resistance of Q-meter is 0.1 R, then the measure Q of the coil would be 1.1 time the actual Q.
2. If the inductance to be measured is less than 0.1 mH, the error due to presence of residual inductance cannot be neglected.
3. The presence of distributed capacitance in a coil modifies the effective Q of the coil.
Which of the above statements are correct?
a) 1, 2 and 3
b) 1 and 2 only
c) 2 and 3 only
d) 1 and 3 only

Ans: Option c)

78. What is an advantage of an electronic voltmeter over a non-electronic voltmeter?
a) Low power consumption
b) Low input impedance
c) The ability to measure wide ranges of voltages and resistances
d) Large Portability

Ans: Option a)

79. An average response rectifier type electronic voltmeter has a d.c. voltage of 10 V applied to it. What is the meter reading?
a) 7.1 V
b) 10 V
c) 11.1 V
d) 22.2 V

Ans: Option c)

80. Which one of the following oscillators is used for the generation of high frequencies?
a) R-C phase shift oscillator
b) Wien bridge oscillator
c) L-C oscillator
d) Blocking oscillator

Ans: Option c)

81. Which of the following transducers requires a high input impedance pre-amplifier for proper measurements?
a)Thermocouple
b) Piezoelectric
c) Thermistor
d) L.V.D.T

Ans: Option b)

82. In a digital voltmeter the oscillator frequency is 400 kHz and the ramp voltage falls from 8 V to 0 V in 20 ms. What is the number of pulses counted by the counter?
a) 800
b) 2000
c) 4000
d) 8000

Ans: Option d)

83. Which of the following cannot provide as much time interval accuracy as the oscilloscope but can capture and display eight or more signals simultaneously, something that scopes cannot do?
a) Logical Analyzer
b) Digital Oscilloscope
c) Frequency Analyzer
d) Wave Analyzer

Ans: Option a)

84. Which of the following transducers is most suitable for monitoring continuous variations in very fine thickness of a material?
a) Diaphragm
b) Capacitor
c) L.V.D.T
d) Piezoelectric crystal

Ans: Option b)

85. Consider the following statements about ultrasonic flowmeters:
1. The measurement is insensitive to viscosity, pressure and temperature variations.
2. It has bidirectional measuring capability and can be used for any pipe size.
3. It has a relatively lower cost.
4. It has good accuracy, fast response and wide frequency range.

Which of the above statements is/are correct?
a) 1 only
b) 1 and 2 only
c) 1, 2 and 4
d) 3 and 4 only

Ans: Option c)

86.

Ans: Option b)

87.






Ans: Option c)

88.

Ans: Option c)


89.

Ans: Option c)

90.

Ans: Option d)

91.

Ans: Option b)


92.

Ans: Option a)

93.

Ans: Option b)


94.

Ans: Option b)

95.

Ans: Option d)


96.

Ans: Option b)

97.

Ans: Option a)

98.



Ans: Option c)

99.


Ans: Option a)

100.

Ans: Option b)

101.

Ans: Option a)

102.

Ans: Option c)

103.

Ans: Option d)

104.

Ans: Option a)

105.

Ans: Option c)

106.

Ans: Option d)

107.

Ans: Option d)

108.

Ans: Option a) & c)

109.

Ans: Option c)

110.

Ans: Option b)

PSU MCQs on Electromagnetics

1. An Antenna that is circularly polarized is the
a) Helical
b) Small circular loop
c) Parabolic reflector
d) Yagi-uda

Ans: Option a)

2. The standard reference antenna for the directive gain is the
a) Infinitesimal dipole
b) Isotropic antenna
c) Elementary doublet
d) Half-wave dipole

Ans: Option b)

3. Top loading is sometimes used with an antenna in order to increase
a) Effective height
b) Bandwidth
c) Beam width
d) Input Capacitance

Ans: Option a)

4. A helical antenna is used for satellite tracking because of its
a) Circular polarization
b) Maneuverability
c) Broad bandwidth
d) Good front-to-back ratio

Ans: Option a)

5. The directivity of an isotropic antenna is
a) Zero
b) Less than unity
c) Unity
d) Infinity

Ans: Option c)

6. In order to receive a vertically polarized wave the conductor of the dipole should be mounted
a) Horizontally
b) Vertically
c) At an angle of 45^o
d) None of these

Ans: Option b)

7. For a dipole antenna
a) The radiation intensity is maximum along the normal to the dipole axis
b) The current distribution along its length is uniform irrespective of the length
c) The effective length equals to its physical length
d) The input impedance is independent of the location of the feed point

Ans: Option a)

8. Two isotropic antennas are separated by a distance of two wavelengths. If both the antennas are fed with currents of equal phase and magnitude, the number of lobes in the radiation pattern in the horizontal plane is
a) 2
b) 4
c) 6
d) 8

Ans: Option d)

9. Consider the following statements:
1.Antenna radiates energy
2. An antenna is a transition device or transducer between a guided wave and free space or vice-versa
3. The resonators and transmission lines store energy
4. An antenna converts electromagnetic signal into current and vice-versa
Which of the following statements are correct?
a) 1,2 and 4 only
b) 1,2 and 3 only

c) 2,3 and 4 only
d) 1,2,3 and 4

Ans: Option a)

10. An antenna can be made more directional by
a) Increasing its diameter
b) Increasing frequency of transmission
c) either a) or b)
d) none of the above

Ans: Option c)

11. The radiation resistance of a circular loop of a turn is 0.01 Ω. The radiation resistance of five turns of such a loop will be
a) 0.002 Ω
b) 0.01 Ω
c) 0.05 Ω
d) 0.25 Ω

Ans: Option c)

12. Far field of an antenna varies with distance r as
a)     1/r
b)     1/r²

c)    1/r³

d)     1/√r

Ans: Option a)

13. Cassegrain feed is used with a parabolic antenna in order to
a) increase the gain of the system
b) Increase the beamwidth of the system
c) Reduce the size of the main reflector
d) Allow the feed to be placed at a convenient point

Ans: Option d)

14. For a plane wave propagating in an unbounded medium (free space), the minimum angle between electric and magnetic field vectors is
a) 0
b) 60
c) 90
d) 180

Ans: Option c)

15. The main difference between the operation of transmission lines and waveguides is that
a) The latter are not distributed, like transmission line
b) The former can use stubs ans quarter-wave transformers, unlike the latter
c) Transmission lines use the principal mode of propagation and therefore do not suffer from low frequency cutoff
d) Terms such as impedance matching and standing wave ratio cannot be applied to waveguides

Ans: Option c)

16. The wavelength of a wave in a waveguide 
a) is greater than in free space
b) depends only on the waveguide dimensions and the free space wavelength
c) is inversely proportional to the phase velocity
d) is directly proportional to the group velocity

Ans: Option a)

17.  A transmission line whose characteristic impedance is a pure resistance 
a) must be a lossless line
b) must be a distortionless line
c) May not be a lossless line
d) May not be a distortionless line

Ans: Option a)

18. A 300 Ω line is terminated in a load impedance of 100 + j 200 Ω. The voltage reflection coefficient is
a) 0.6325 ∟108
b) 0.7 ∟30
c) 0.27 + j 0.196
d) 0.377 ∟42.7

Ans: Option a)

19. 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

Ans: Option d)

20. An electromagnetic wave incident on a perfect conductor is 
a) Entirely reflected
b) Fully transmitted
c) Partially transmitted
d) None of these
Ans: Option a)

21. Which one of the following sets of equations is independent in maxwell's equations?
a) Two curl equations
b) two divergence equations
c) Both the curl and divergence equations 
d) two curl equations combined with the continuity equation 

Ans: Option c)

22. Consider the following statements:
For electromagnetic waves propagating in free space:
1. Electric field is perpendicular to direction of propagation
2. Electric field is along the direction of propagation
3. Magnetic field is perpendicular to direction of propagation
4. Magnetic field is along the direction of propagation
Which of these statements are correct?
a) 1 and 3
b) 1 and 4
c) 2 and 3
d) 2 and 4

Ans: Option a)

23. The dominant mode in a rectangular waveguide is TE10 because this mode has
a) No attenuation
b) No cut-off
c) No magnetic field component
d) The highest cut-off wavelength

Ans: Option d)

24. 8-point charges of 1nC each are located at the corners of a cube in free space that on 1m on a side, then  at the center is
a) 0 V/m
b) 5 V/m
c) 4 V/m
d) -5 V/m

Ans: Option a)

25. A 50 Ω lossless transmission line has a pure reactance of j100 Ω as its load. The VSWR in the line is 
a) 0
b) Infinity
c) 50
d) 100 + j 100

Ans: Option b)

26. Calculate the front-to-back ratio of an antenna in dB which radiates 3 kW in its optimum direction and 500 watts in the opposite direction
a) 0.782
b) 7.782
c) -22.22
d) none of these

Ans: Option b)

27. An uniform plane wave incident normally on a plane surface of dielectric material is reflected with a VSWR of 3. What is the percentage of incident power that is reflected.
a) 10%
b) 25 %
c) 50%
d) 75%

Ans: Option b)

28. Two coaxial cables 1 and 2 are filled with different dielectric constants ϵr1 and ϵr2 respectively. The ratio of the wavelengths in the two cables λ1/ λ2 is 
a) √( ϵr1/ ϵr2)
b) √( ϵr2/ ϵr1)
c) ϵr1/ ϵr2
d) ϵr2/ ϵr1

Ans: Option b)


29. Which of the following is zero?
a) Grad div
b) Div grad
c) Curl grad
d) Curl curl

Ans: Option c)

30. Which is not an example of convection current?
a) A moving charged belt
b) Electronic movement in a vacuum tube
c) An electron beam in a television tube
d) Electric current flowing in a copper wire

Ans: Option d)

31. One of the following is not a source of magnetostatic fields
a) A dc current in a wire
b) A Permanent magnet
c) An accelerated charge
d) An Electric filed linearly changing with time

Ans: Option c)

32. Which of thse statements is not characteristic of a static magnetic field?
a) It is solenoidal
b) It is conservative
c) It has no sinks or sources
d) Magnetic flux lines are always closed

Ans: Option b)
Static magnetic field is not conservative

33. Two thin parallel wires carry currents along the same direction. The force experienced by one due to the other is
a) Parallel to the lines
b) Perpendicular to the lines and attractive
c) Perpendicular to the lines and repulsive
d) Zero

Ans: Option b)

PSU MCQs on Satellite Communication and Radar

1. Most satellites operate in the frequency range of
a) 300 MHz to 3 GHz
b) 30 MHz to 300 MHZ
c) Above 300 GHz
d) 3 GHz to 30 GHz

Ans: Option d)

2. The frequency band used by most satellite is
a) UHF
b) VHF
c) SHF
d) EHF

Ans: Option c)
Super High Frequency:  3 to 30 GHz

3. The bandwidth of a typical satellite is
a) 500 MHz
b) 900 MHz
c) 200 MHz
d) None of these

Ans: Option a)

4. For satellite communication, the frequency should be
a) Less than the critical frequency of ionosphere
b) Equal to the critical frequency of ionosphere
c) More than the critical frequency of ionosphere
d) None of these

Ans: Option c)

5. Geostationary satellites follow
a) circular path
b) elliptical path
c) inclined path
d) cycloidal path

Ans: Option b)

6. A synchronous satellite orbits the earth once in
a) 24 hours
b) 12 hours
c) 6 hours
d) 1 hour

Ans: Option a)

7. The distance of a geostationary satellite from the surface of the earth is nearly
a) 360 Km
b) 3600 Km
c) 36,000 Km
d) 3,60,000 Km

Ans: Option c)

8. Satellite sends back signals to earth by means of
a) Yagi antenna
b) chicken-mesh antenna
c) horn antenna
d) dipole antenna

Ans: Option c)
Satellite sends back signals through horn antenna

9. In satellite communication
a) Amplitude modulation is used
b) Frequency modulation is used
c) Pulse width modulation is used
d) Pulse Amplitude modulation is used

Ans: Option b)

10. Antenna elevation angle at the ground station for satellite communication is always kept above 5^o to
a) minimize the sky noise temperature
b) reduce the effect of oxygen and water vapour absorption on the antenna noise temperature
c) minimize the slant range
d) increase the visibility of the satellite

Ans: Option d)

11. For global communication, the minimum number of satellite needed is
a) one
b) three
c) seven
d) eleven

Ans: Option b)
One satellite can see "one-third" of the globe

12. FM is preferred for satellite communication because
a) satellite channel has large bandwidth and less noise
b) It gives high modulation index
c) low bandwidth is essentially required
d) Other methods of modulation will result in fading and distortion

Ans: Option a)

13. In a satellite system:
a) upward link frequency is half of downward link frequency
b) upward link frequency is greater than that of downward link frequency
c) upward link frequency is lesser than that of downward link frequency
d) upward link frequency is equal to downward link frequency

Ans: Option b)

14. A geostationary satellite
a) remains stationary in space
b) remains at a height of 1000 km above the surface of earth
c) orbits the earth with 24 hour period
d) remains always in a direction opposite to that of sun, with respect to earth

Ans: Option c)

15. Satellite communication links are preferred over sub-marine cables because
a) they are faster
b) they involve lesser cost
c) of their multiple access ability
d) none of these

Ans: Option c)

16. The satellite orbit almost invariably used with remote sensing satellite is:
a) geostationary orbit
b) geosynchronous orbit
c) sun synchronous orbit
d) Molniya orbit

Ans: Option c)

17. The beam width required for a satellite antenna for full global coverage is approximately
a) 1
b) 5
c) 18
d) 4

Ans: Option c)

18. A satellite earth station antenna having a maximum gain of 60 dB at the operational frequency is fed from a power amplifier generating 10 KW. If the feed system has a loss of 2 dB, determine earth station EIRP(Effective Isotropic Radiated Power)

a) 98dBW
b) 100 dBW
c) 89 dB
d) 98 dB

Ans: Option a)

19.  A radio communication link is to be established via the ionosphere. The virtual height at the midpoint of the path is 300 km and the critical frequency is 9 MHz. The maximum usable frequency for the link between the stations of distance 800 km assuming flat earth is
a) 11.25 MHz
b) 12 MHz
c) 15 MHz
d) 25.5 MHz

Ans: Option c)

20. If a satellite is launched at an orbital radius of twice that of a geostationary satellite, how much time will the launched satellite take to travel around the earth
a) 48 hrs
b) 12 hrs
c) 96 hrs
d) 6 hrs

Ans: Option c)

T² α r³ by kepler’s law

Since the time period of geostationary satellite is 24 hrs

(T/24)² = 2³

T  = 67.88 hrs

20. Which of the following techniques not suitable for automatic satellite tracking?
a) Monopulse
b) Step-track
c) Conical Scanning
d) Lobe switching

Ans: Option b)

21. Which of the following statements is not correct?
a) A geo-synchronous satellite remains practically stationary relative to earth antennas
b) A geo-synchronous satellite means the same thing as geo-stationary satellite
c) There is a trade-off between the cost of a communication satellite and cost of its earth stations
d) Three geo-synchronous satellites cannot give 100% global coverage.
Ans: Option d)

22. Which ionosphere layer is responsible for return of a radiation at frequency 30 MHz?
a) D
b) E
c) F
d) All the above

Ans: Option c)

23. Communication satellites are allotted bandwidth of 500 MHz. This can be increased by using
a) Frequency and Polarization re-use
b) Time division Multiplexing
c) Frequency division Multiplexing
d) Triple modular redundancy

Ans: Option a)

24. What does a link budget for satellite communication include
a) Total cost of satellite
b) Cost of satellite plus launch vehicle
c) Signal and noise levels in dB
d) Margins of error permitted

Ans: Option: c)

25. The output stage of a transponder on-board a satellite has a maximum power output of 10 watts. However, it is not operated at the maximum power output in order to
a) Conserve the available limited battery power
b) Reduce noise due to device
c) Avoid inter-modulation distortion
d) Avoid heating up of the satellite beyond a preset value

Ans: Option a)

RADAR

1) The term RADAR stands for
a) Radio direction and reflection
b) Radio waves dispatching and receiving
c) Random detection and re-radiation
d) Radio detection and ranging

Ans: Option d)

2) Frequency in UHF range propagate by means of
a) Ground waves
b) Sky waves
c) Surface waves
d) Space waves

Ans: Option d)

3) Which of the following diode is used as a detector in a RADAR?
a) Gunn Diode
b) Schottky diode
c) IMPATT diode
d) Any of the above

Ans: Option c)

4) Most of the aircraft surveillance Radars operate in
a) X-band
b) C-band
c) L-band
d) S-band

Ans: Option c)

5) In case of RADAR receiver the IF bandwidth is inversely proportional to
a) Pulse interval
b) Pulse repetition frequency
c) square root of peak transmitted power
d) Pulse width

Ans: Option d)

6) Radar detection is limited to line of sight because
a) Of curvature of the earth
b) The waves are not reflected by the ionosphere
c) Long wavelengths are used
d) Short wavelengths are used

Ans: Option a)

7) To increase the radar range of ground and surface targets to see well beyond the normal radar horizon, the electromagnetic wave propagation adopted is
a) Ionosphere scatter
b) Tropo Scatter
c) Ground wave propagation
d) Duct

Ans: Option b)

8) Troposphere scatter is used with frequencies in the following range
a) HF
b) VHF
c) UHF
d)VLF

Ans: Option c)

9)  A Radar receives an echo from a target 20 microseconds after sending the signal. The approximate range of the target is
a) 300 m
b) 3000 m
c) 600 m
d) 6000 m

Ans: Option b)

Range= cT/2 = 3x10⁸ x 20 x 10^-6/2 = 6000/2 = 3000 m

10) Which of the following can be used to improve range resolution in a Radar?
a) Short duration pulse
b) Long duration pulse
c) High frequency of operating signal
d) Increasing bandwidth

Ans: Option a)

11) In a radar system, if the peak transmitted power is increased by a factor of 16 and the antenna diameter is increased by a factor of 2, then the maximum range will increase by a factor of
a) 16
b) 8
c) 4
d) √8

Ans: Option c)

R_max α [ P_t A_e ²]^1/4

R_max α [ P_t D⁴]^1/4

[16 x 16] ^1/4=4

12) For identifying a radar target in a non-lossy medium, the range of the target is to be doubled, the RF power radiated must be increased by

a) 2 times

b) 4 times

c) 8 times

d) 16 times

Ans: Option d)

R_max α [ P_t ]^1/4

R_max α [ 16]^1/4

^{13) An Altimeter is basically} 

^{a) a CW Radar}

^{b) a FM Radar}

^{c) a Doppler Radar}

^{d) a device to indicate the direction at height}

^{Ans: Option a)}