Quiznetik

Electromagnetics | Set 1

1. Gradient of a function is a constant. State True/False.

Correct : B. false

2. The mathematical perception of the gradient is said to be

Correct : C. slope

3. Divergence of gradient of a vector function is equivalent to

Correct : A. laplacian operation

4. Curl of gradient of a vector is

Correct : C. null vector

5. Find the gradient of the function given by, x2 + y2 + z2 at (1,1,1)

Correct : B. 2i + 2j + 2k

6. The gradient can be replaced by which of the following?

Correct : C. differential equation

7. . Find the gradient of the function sin x + cos y.

Correct : A. cos x i – sin y j

8. The divergence of a vector is a scalar. State True/False.

Correct : A. true

9. The divergence concept can be illustrated using Pascal’s law. State True/False.

Correct : A. true

10. Compute the divergence of the vector xi + yj + zk.

Correct : D. 3

11. Find the divergence of the vector yi + zj + xk.

Correct : B. 0

12. Find the divergence of the vector F= xe-x i + y j – xz k

Correct : A. (1 – x)(1 + e-x)

13. Find whether the vector is solenoidal, E = yz i + xz j + xy k

Correct : A. yes, solenoidal

14. Find the divergence of the field, P = x2yz i + xz k

Correct : B. 2xyz + x

15. Identify the nature of the field, if the divergence is zero and curl is also zero.

Correct : C. solenoidal, irrotational

16. Curl is defined as the angular velocity at every point of the vector field. State True/False.

Correct : A. true

17. The curl of curl of a vector is given by,

Correct : B. grad(div v) – (del)2v

18. Which of the following theorem use the curl operation?

Correct : C. stoke’s theorem

19. The curl of a curl of a vector gives a

Correct : B. vector

20. Is the vector is irrotational. E = yz i + xz j + xy k

Correct : A. yes

21. Find the curl of A = (y cos ax)i + (y + ex)k

Correct : B. i – ex j – cos ax k

22. Find the curl of the vector A = yz i + 4xy j + y k

Correct : D. i + yj + (4y – z)k

23. Curl cannot be employed in which one of the following?

Correct : D. waveguides

24. Which of the following Maxwell equations use curl operation?

Correct : A. maxwell 1st and 2nd equation

25. The integral form of potential and field relation is given by line integral. State True/False

Correct : A. true

26. If V = 2x2y – 5z, find its electric field at point (-4,3,6)

Correct : B. 57.905

27. Find the potential between a(-7,2,1) and b(4,1,2). Given E = (-6y/x2 )i + ( 6/x) j + 5 k.

Correct : C. -8.214

28. A field in which a test charge around any closed surface in static path is zero is called

Correct : D. conservative

29. The potential in a lamellar field is

Correct : B. 0

30. Line integral is used to calculate

Correct : D. length

31. The energy stored in the inductor 100mH with a current of 2A is

Correct : A. 0.2

32. Gauss law for electric field uses surface integral. State True/False

Correct : A. true

33. Surface integral is used to compute

Correct : B. area

34. Coulomb’s law can be derived from Gauss law. State True/ False

Correct : A. true

35. Evaluate Gauss law for D = 5r2/4 i in spherical coordinates with r = 4m and θ = π/2.

Correct : C. 588.9

36. The ultimate result of the divergence theorem evaluates which one of the following?

Correct : D. charge and flux

37. The divergence theorem converts

Correct : B. surface to volume integral

38. The triple integral is used to compute volume. State True/False

Correct : A. true

39. The volume integral is three dimensional. State True/False

Correct : A. true

40. Using volume integral, which quantity can be calculated?

Correct : C. volume of cube

41. Gauss theorem uses which of the following operations?

Correct : C. divergence

42. The Gauss divergence theorem converts

Correct : D. surface to volume integral

43. Find the divergence theorem value for the function given by (ez, sin x, y2)

Correct : B. 0

44. Divergence theorem computes to zero for a solenoidal function. State True/False.

Correct : A. true

45. Coulomb is the unit of which quantity?

Correct : B. charge

46. Coulomb law is employed in

Correct : A. electrostatics

47. Find the force between 2C and -1C separated by a distance 1m in air(in newton).

Correct : B. -18 x 106

48. Two charges 1C and -4C exists in air. What is the direction of force?

Correct : C. from 1c to -4c

49. The Coulomb law is an implication of which law?

Correct : B. gauss law

50. For a charge Q1, the effect of charge Q2 on Q1 will be,

Correct : B. f1 = -f2

51. The electric field intensity is defined as

Correct : C. force per unit charge on a test charge

52. Find the force on a charge 2C in a field 1V/m.

Correct : C. 2

53. Electric field intensity due to infinite sheet of charge σ is

Correct : D. σ/2ε

54. For a test charge placed at infinity, the electric field will be

Correct : C. zero

55. The lines of force are said to be

Correct : C. drawn to trace the direction

56. Electric flux density in electric field is referred to as

Correct : B. ratio of flux lines crossing a surface and the surface area

57. The electric flux density is the

Correct : A. product of permittivity and electric field intensity

58. Which of the following correctly states Gauss law?

Correct : D. electric flux per unit volume is equal to volume charge density

59. The Gaussian surface is

Correct : B. imaginary surface

60. A point charge 2nC is located at origin. What is the potential at (1,0,0)?

Correct : D. 18

61. Find the potential of V = 60sin θ/r2 at P(3,60,25)

Correct : A. 5.774

62. The potential difference in an open circuit is

Correct : C. infinity

63. The potential taken between two points across a resistor will be

Correct : B. negative

64. What is the potential difference between 10sinθcosφ/r2 at A(1,30,20) and B(4,90,60)?

Correct : C. 4.386

65. The voltage at any point in an ac circuit will be

Correct : B. rms voltage

66. Divergence theorem is based on

Correct : A. gauss law

67. The Gaussian surface for a line charge will be

Correct : B. cylinder

68. The Gaussian surface for a point charge will be

Correct : C. sphere

69. The total charge of a surface with densities 1,2,…,10 is

Correct : C. 55

70. The work done by a charge of 10μC with a potential 4.386 is (in μJ)

Correct : B. 43.86

71. Gauss law cannot be used to find which of the following quantity?

Correct : D. permittivity

72. Gauss law for magnetic fields is given by

Correct : B. div(b) = 0

73. Gauss law can be used to compute which of the following?

Correct : C. radius of gaussian surface

74. Gauss law can be evaluated in which coordinate system?

Correct : D. depends on the gaussian surface

75. Gauss law cannot be expressed in which of the following forms?

Correct : D. stokes theorem

76. With Gauss law as reference which of the following law can be derived?

Correct : C. coulomb’s law

77. The electric flux density and electric field intensity have which of the following relation?

Correct : A. linear

78. Find the potential at a point (4, 3, -6) for the function V = 2x2y + 5z.

Correct : B. 66

79. Find the potential of the function V = 60cos θ/r at the point P(3, 60, 25).

Correct : B. 10

80. Find the work done moving a charge 2C having potential V = 24volts is

Correct : D. 48

81. The distance vector is obtained in

Correct : D. space coordinate system

82. The divergence of distance vector is

Correct : B. 3

83. Find a vector normal to a plane consisting of points p1(0,1,0), p2(1,0,1) and p3(0,0,1)

Correct : A. –j – k

84. The unit vector to the points p1(0,1,0), p2(1,0,1), p3(0,0,1) is

Correct : A. (-j – k)/1.414

85. The polar form of Cartesian coordinates is

Correct : A. circular coordinates

86. The work-electric field relation is given by

Correct : C. line integral

87. The distance vector can be used to compute which of the following?

Correct : C. unit normal vector

88. Distance and position vectors rely on field strength. State True/False.

Correct : A. true

89. Find the projection of A on B. Given A = 10j + 3k and B = 4j + 5k.

Correct : B. 6.25

90. The del operator is called as

Correct : D. vector differential operator

91. The relation between vector potential and field strength is given by

Correct : A. gradient

92. The Laplacian operator is actually

Correct : B. div(grad v)

93. The divergence of curl of a vector is zero. State True or False.

Correct : A. true

94. The curl of gradient of a vector is non-zero. State True or False.

Correct : B. false

95. Identify the correct vector identity.

Correct : C. div (u x v) = v . curl(u) – u . curl(v)

96. A vector is said to be solenoidal when its

Correct : A. divergence is zero

97. The magnetic field intensity is said to be

Correct : C. solenoidal

98. A field has zero divergence and it has curls. The field is said to be

Correct : B. solenoidal, rotational

99. When a vector is irrotational, which condition holds good?

Correct : B. stoke’s theorem gives zero value

100. The Cartesian system is also called as

Correct : B. rectangular coordinate system