# Electromagnetics and Field Theory Part One

1. Two parallel plates are separated by a distance D charged by V volt. The field intensity E is given by,
1. V / D
2. V²/ D
3. V × D²
4. V × D

2. As
a result of reflection from a plane conducting wall, electromagnetic
waves acquire an apparent velocity greater than the velocity of light in
space. This is called the

1. normal velocity.
2. phase velocity.
3. group velocity.
4. velocity of propagation.

3. Inside a hollow conducting sphere
1. electric field changes with distance from the center of the sphere.
2. electric field is zero.
3. electric field changes with magnitude of the charge given to the conductor.
4. electric field is a non zero constant.

4. Electric field intensity (E) at ant point in an electric field is equal to

5. An
electric field on a place described by its potential V = 20(r⁻¹ + r⁻² )
where r is the distance from the source. The field is due to

1. A dipole.
2. Both A dipole & A monopole
3. A monopole.
4. A quardra pole.

6. Two
point charges are in the vertex of the square. If potential is another
vertex is 2 V, so potential in opposite vertex (diagonally) is

1. 2 V.
2. √ 2 V.
3. 1 V.
4. Zero.

7. A
metal sphere with 1 m radius and a surface charge density of 10
coulombs / m² is enclosed in a cube of 10 m side. The toatal outward
electric displacement normal to the surface of the cube is.

1. 5 C.
2. 10 C.
3. None of these
4. 40π C.

8. An
electric dipole of moment P is placed in front of a ground sphere. The
change induced on the surface of the sphere is (Assume radius of sphere =
R and distance from dipole to centre of sphere = d)

1. PR/d.
2. Zero.
3. PR²/d³.
4. PR/d².

9. What is the value of total electric flux coming out of a closed surface?
1. Equal to the surface charge density.
2. Equal to total charge enclosed by the surface.
3. Equal to volume change density.
4. Zero.

10. Electric field strength of charge
1. Decrease with square distance.
2. Decrease with distance.
3. Increase distance.
4. Increase square distance.

11. The statement which is not correct from the following:
1. An electric flux line is an imaginary path or a line drawn in such a
way, that its direction at any point is the direction of electric field
at that point.
2. Gauss’s law static that total electric flux through any surface is equal to the total charge enclosed by surface.
3. Gauss’s static that divergence of D = ρu.
4. For a uniform long charged line with l1 c/m the electric field intensity E is given as E = ρL/(π ε₀.r).

12. Two infinite parallel metal plates are charged with equal surface charge density of the same plates is.
1. Double of field produced by one plate.
2. Dependent on coordinates of field point.
3. The same as that produced by one plate.
4. Zero.

13. An insulated metal sphere of 20 cm diameter is charged by rubbing with charges 2 × 10⁻⁸ C. Potential developed will be
1. 2.88 V.
2. 28.8 V.
3. 14.40 V.
4. 1.4 V.

14. Which of the following statement are incorrect?
1. A dielectric material is liner if ε does not change with applied field.
2. In a liner dielectric P varies linearly with E.
3. A dielectric material is isotropic if &elipson; does not change with direction.
4. A conductor is an equipotential body and E is always tangential to the conductor.

15. Between a hollow and solid metal sphere, charge reside
1. On outer surface in both.
2. On outer surface in solid and throughout hollow.
3. On outer surface in hollow and throughout is solid.
4. None of above.

16. The electric flux is given D = (2y² + z) Ix + 4xy Iy + x 1z C/m². The volume charge density at point (-1,0,3) is
1. – 2 C/m³.
2. – 8 C/m³.
3. 0 C/m³.
4. – 4 C/m³.

17. Gradient of scalar field is expressed as
1. Circulation of a vector field per unit area as the area tends to zero.
2. Outward flux of a vector field per unit volume as the volume about the point tends to zero.
3. Gradient of divergence of a vector field minus the curl of the vector field.
4. Maximum rate of increase of scalar function at appoint.

18. A vector field A = p 1 n is given in Cartesian coordinates. In cylindrical coordinates it will be represented as
1. A = cosφ 1r + sinφ Iφ.
2. A = sinφ 1r.
3. A = cosφ 1r – sinφ 1r.
4. A = cosφ 1r.

19. A potential field is given by V = 3x²y –yz. The electric field at P(2, -1, 4) is
1. 12 1x – 8 1y V/m.
2. 12 1x – 1z V/m.
3. 12 1x – 8 1y – 1z V/m.
4. 12 1x + 8 1y + 1z V/m.

20. A sphere of radius with a uniform charge density ρv C/m³ shall have electric flux density at the radius r = a equal to
1. aρ C/m².
2. ρ/3 C/m².
3. aρv/4 C/m².
4. aρ/3 C/m².

21. An infinite sheet has a charge density of 150 μ C/m. The flux density in μ C/m² is
1. 1/75.
2. 75.
3. 50.
4. 100.

22. If
in a 1 mF capacitor, an instantaneous displacement current of 1 A is to
be established in the spaces between its plates then it is possible by

1. 10⁶ Amp/see.
2. 10⁶ volts/see.
3. 10⁶ volts.
4. 10⁶ Amp.

23. The work done by a force = 4un – 3uy + 2uz N in giving a inc charge a displacement of (10 ux + 2uy – 7uz) m is
1. 100 nj.
2. 40 nj.
3. 20 nj.
4. 60 nj.

24. Which statement does not say that electrostatic field conservative?
1. If is gradient of a scalar potential.
2. The work done in a closed path inside the fields is zero.
3. If the curl of E is identically zero.
4. The potential difference between two points is zero.

25. A
circular ring carrying uniformly distributed charge q and a point
charge – Q on the axis of the ring. The magnitude of dipolement of the
charge system is (Assume distance between centre of ring and point
charge is d and radius of ring R)

1. QR.
2. Q√(R⁶ + d⁶).
3. QD.
4. QR⁶/d.

26. If E is the electric field intensity, then what is the value of divergence of (curl of E)?.
1. Null vector.
2. Zero.
3. E.
4. | E |.

27. A
sphere of zoo radius contains electrical charge of density 2/(r sinθ)
c/m³. What is the total charge contained within the sphere?

1. 0.
2. None of these.
3. 0.335/sinθ c.
4. 0.335 C.

28. Two sphere of radius r1 and r2 are connected by a conducting wire. Each of the spheres has been given a charge Q. Now
1. Both of sphere will have same potential.
2. Larger sphere will have greater potential.
3. Larger sphere will have smalled potential.
4. Smaller sphere will have zero potential.

29. In frec space E (z,t) = 10³ sin(ωt – βz) uy v/m. What is the value of H (z,t)
1. (10³/377) sin(ωt – β z)(-uy) A/m.
2. (10³/377) sin(ωt – β z)(-ux) A/m.
3. None of these
4. (10³/377) cos(ωt – β z)(-ux) A/m.

30. n a lossless medium the intrinsic impedance η 60π and μr = 1. The relative dielectric constant εr shall be
1. 8.
2. 4.
3. 1.
4. 2.

31. A plane wave magnetic field is represented by Bx = cos(y – ct). The electric and magnetic fields will be zero in the direction
1. Ex = Ey = 0, By = Bz = 0.
2. Ey = Ez = 0, By = Bz = 0.
3. None of these.
4. Ex = Ey = 0, Bx = By = 0.

32. What is the value of skin depth as 100 Hz in a material having μr = 1.0 and &sigma = 3.60 × 10⁷ s/m
1. 4 mm.
2. 2.4 mm.
3. 10 mm
4. 8.4 mm.

33. kin depth is proportional to
1. Frequency.
2. √(σ).
3. Permeability.
4. 1/√σ.

34. If n is the polarization vector and k is the direction of propagation plane electromagnetic wave, them
1. n × k =0.
2. n = K.
3. n = – k.
4. n.k =0.

35. A
solid sphere made of insulating material has a radius R and has a total
charge Q distributed uniformly in its volume. What is the magnitude of
electric field intensity, E, at a distance r (o less than r less than R)
inside the sphere

1. 3 Qr/(4 π εo R³).
2. Q/(4 π εo r³).
3. QR/(4π εo r³)
4. Qr/(4 π εo R³).

36. For a line characteristic impedance zo terminated is load zo/3, the reflection coefficient is
1. 1/3.
2. – ½.
3. 2/3.
4. – 1/3.

37. Find H for centre of solenoid having finite length d = 1 unit where N = no of turns = 500, 1 = 2 A.
1. None of these
2. 1000.
3. 500.
4. 100.

38. A magnetic vector potential is given by the expression A = (- cos x) (cos y) uz. The flux density at the origin is
1. – 2 ux.
2. 2 ux.
3. – uy.
4. 0.

39. The Kirchhoff’s current law is implict in expression
1. Curl of H = J + (δ D)/(δ t).
2. Surface integral of (j.ds) = 0.
3. Divergence of B = 0.
4. Divergence of D = ρv.

40. A
rectangular loop in the x – z plane bounded by the lines x=o, x=a, z=o
and z=b is in a time varying magnetic field is given by B=Bo cosω + ay.
Where Bo is constant, ω is angular frequency and ay unit vector in the y
direction. Now the emf induced in the loop is given

1. Bo ω sinω t.
2. ab Bo cosω t.
3. abω Bo sinω t.
4. Zero.

41. The
force on a charge moving with velocity v under the influence of
electric and magnetic fields is given by which one of the following

1. q(E + V) × B).
2. q(H + V × E).
3. q(E + B × V).
4. q(E +V × H).

42. Which is the major factor for determining whether a medium is free space, lossless dielectric or a good conductor
1. Loss tangent.
2. Reflector coefficient.
3. Constitutive parameters.
4. Attenuation constant.

43. If the static magnetic flux density is B, then
1. Curl of B = J.
2. Curl of B = 0.
3. Divergence of B = J.
4. Divergence of B = 0.

44. Which of the following statement for a divergence of electric and magnetic flux densities
1. It is zero for the electric flux density.
2. These are zero for static densities but non zero for time varying densities.
3. It is zero for the magnetic flux density.
4. Both are zero.

45. Poyniting vector has the dimensions
1. none of these
2. Watts/metre².
3. Wall/metre².
4. Watt/metre.

46. For a linear electromagnetic circuit, which of the following statement is true?
1. Field energy is lesser than the co-energy.
2. Field energy is greater than the co-energy.
3. Co-energy is zero.
4. Field energy is equal to the co-energy.

47. A conductor is rotating with in a magnetic field. At which of the positions do the peak voltages occur?
1. Anywhere.
2. At 45 Â° angles to the axis of the magnetic field.
3. Along the axis of the magnetic field.
4. At right angles to the axis of the magnetic field.

48. The electric field intensity of an equipotential surface is
1. always perpendicular to the surface
2. zero
3. None of these.
4. always parallel to the surface

49. he surface integral of electric field intensity gives
1. flux density
2. net charge enclosed by the surface
3. None of these
4. net flux imanating out from the surface