**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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