Friday, 22 April 2016

Electromagnetic Multiple Choice Questions and Answers - ECE interview questions and answers pdf

Electromagnetic Interview Questions and Answers 

1)      A long wire carrying 100 amp is placed in an external external magnetic field of 50 gauss.

        The wire is at right angles to the field
2) The frequencies in ultra high frequency range are propagated by means of
3) An electromagnetic wave incidents on a perfect insulator at an angle. If the wave is not entirely parallel polarised, then
4) The force in a magnetic field is given by F = qvB.
5) A wire 1 m long carries a current of 5 amp and is at an angle of 30° with B = 1.5 Wb/metre2
        The magnitude of the force and its direction are
6)      The electric flux of a hemisphere of radius R and electric field E is
7)      The following wave does not exist in waveguides:
8)      A crow is sitting on a conductor carrying 11,000 volts.
9)      Poynting vector gives the :
10)     A beam of protons is deflected sideways
11)     Electrons with an energy of 12 keV are shot in a TV tube and acted on by a magnetic field of B = 5.5 x 10-8 Wb/metre". The acceleration is
12)     The relative permeability is taken as unity for
13)     Which of the following is a scalar quantity ? 
14)     A lightning conductor on top of a buildjng is made into a poined spike because
15)     The new magnetic flux emerging from any closed surface is
16)     On doubling the number of turns of a coil the inductance
17. The ground wave eventually disappears, as one moves away from the transmitter because of
18. Which of the following is paramagnetic material ?
19. If a dielectric is placed in an electric field, the field strength :
20. The wave propagation in plasma is known as
21. The following relation is true :
22. Two waves of same frequency have opposite phases when the phase angle between them is
23. The electric charge is transferred from one body to another insulated metal body only when
24.     Two conducting loops one large and another small face each other and 'd' apart. A clockwise current 'i' is suddenly established in the larger loop. The direction of the induced current in the small loop is
25. VSWR is minimum when
26. An electron is placed midway between two equal and opposite charges. The electron will
27. There is a long wire carrying 20 amp. There is a rectangular (30 x 8 cm) loop of wire at a distance of 1 cm with the long side parallel to         the long wire and carryting a current of 10 amp. The resultant force on the loop is
28. The work done in moving a charge Q on an equipotential line for a distance 'd' will be
29. The unit of polarization is the same as that of
30. Dielectric constant and dielectric strength are
31. A copper sheet is placed in a plane perpendicular to B acting from below. A sudden change in B is not detected above the sheet because
32. The electric intensity for free space is given by
33. The electric field strength at any point equals :
34.     The charging and discharging of a RC combination by a battery and switch is seen on a CRO The waveform will be
35.     The rii.k.s. unit of electric displacement density is
36. Volume integral is the :
37. A time varying field is applied to a circuit with a capacitor
38.     A wire of resistance 5 ohms is connected to a battery of emf 2V and internal resistance 1 ohm. In 2 mts, how much energy is transferred from         chemical to electrical form?
39.     In electromagnetic waves, polarization
40. An electromagnetic wave incident on a perfect dielectric is:
41. A combination of left-handed circular polarisation and right-handed polarisation leads to
42.     A dominant wave is characterized by :
43.     The surface integral of the electric field intensity is
44. The unit of magnetic flux density is :
45. There are two charges of +10 and +30 e.s.u. There is a point P between them where the electric field strength is zero. Then the point P.
46.     Mark the false statement
47.     The value of VSWR is taken as 8 when the line is
48. The m.k.s. unit of magnetic flux density is 
49. A perfect conductor is one which has
50. The m.k.s. unit for µ is
51. A range of microwave frequencies more easily passed by the atmosphere than others is called a
52. Which of the following is ferromagnetic material ?
53. The unit of µ0e0 is
54.     Surface impedance at high frequencies is a consideration for
55.     A body can be charged when it is 
56.     Intrinsic impedance of free space is given as
57.     Hysteresis losses
58. A circular parallel plate capacitor of radius R = 10 cm is charged so that the electric field between the plates varies at 10(Power of 13)V/metre sec.
        The displacement current is
59. If the medium of a parallel plate capacitor is mica and air the capacitance increases on :
60. A current is passed through a vertical spring from whose lower end weight is hanging
61.   A current is set up in a long copper pipe. Choose the correct statement.
62. When an electromagnetic wave travelling in one medium strikes upon a second medium (having a different conductivity the wave will be
63.  A surface encloses a dipole, $£ for the surface is
64. The reflection coefficient is generally a
65. The outward displacement through a closed surface equals
66. A solenoid of 4 cm dia and 2 m long is closely wound with a single layer of 10 gauge (0.10 in dia) copper wire. The inductance per unit length at the centre is
67. Wires that carry equal and opposite currents are twisted because
68. Mark the incorrect relation
69.     The relative permeability is slightly more than 1 in case of
70.     The boundary conditions at the interface between two dielectrics in an electric field-are given by
71. Circular polarized waves result when :
72. A parallel plate capacitor is chareed by a battery.
73.  Inductance per unit ienglh for a solenoid near its centre compared to its ends is
74. The polarization of dielectric materials results in
75. Electric field intensity at any point is
76. A conductor and an insulator is heated;
77. Which of the following is a diamagnetic material ?
78. An electro magnetic wave travelling in x direction has EY and EV components at 45° phase apart. The wave can be termed as
79.     A conductor is said to be perfect if it has
80.     In a perfect conductor, the incident and the reflected waves combine to produce :
81.     A charged rod attracts bits of uncharged paper. After touching the rod. they jump violently away from it because
82.     The unit of eo, the permittivity of free space is 
83.     High frequency waves are
84. Hysteresis losses:
85. When electric field is parallel to the place of incidence, the electromagnetic wave u said to be
86. Two vectors A & B are equal if their
87. Which of the following statement is true
88. Which of the following does not characterize a ferromagnetic material ?
89.     A point charge is placed at the centre of a spherical Gaussian surface. The flux fE is changed
90.     The ratio of the tangential component of'the electric field at the surface of conductor and the linear current density which flows as a result of this electric field, is known as
91.     Polarization in electromagnetic wave is caused by 
92. When a wave is incident from the more dense into a less dense medium at an angle equal to or exceeding the critical angle, the wave suffices:
93. The ratio of tangential component of electric field at the surface of a conductor and the linear current density resulting from this field is 
94. When a charge q moves with velocity v in a magnetic field B and an electric field E, the Lorentz force F is given by
95. The wave propagation occurs without attenuation in case of a
96.  Which of the following relation is in correct ?
97. Vectors can be added :
98. The current in a circuit with resistance in 6 amp. When an additional resistance of 4 ohms is inserted, the current drops to 4 amp. The original resistance in ohms is
99. While comparing a magnetic circuit with an electric circuit, the equivalent of the magnetic flux is
100.    When an electromagnetic wave, undergoes reflections from a plane of conducting units, it acquires

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