ELECTROMAGNETIC THEORY(PREVIOUS SET QUESTIONS)

 Module 5. Electromagnetic Theory

 Electrostatics: Gauss’s law and its applications, Laplace and Poissons equations, boundary value problems. Magnetostatics: Biot- Savart law, Ampere’s theorem. Electromagnetic induction. Maxwell’s equations in free space and linear isotopic media; boundary conditions on the fields at interfaces. Scalar and vector potentials, gauge invariance. electromagnetic waves in free space. Dielectrics and conductors. Reflection and refraction, polarization, Fresnel’s law, interference, coherence and diffraction. Dynamics of charged particles in static and uniform electromagnetic fields, Dispersion relations in plasma. Lorentz invariance of Maxwell’s equations. Transmission lines and wave guides. Radiation – from moving charges and dipoles and retarded potentials

PREVIOUS YEAR QUESTION PAPER

SET 2019/7

30. Modified Ampere’s circuital law is expressed as ----(Symbols have their usual

meaning; quantities in bold represent vectors)

A) ∇. J = −dp/dt            B) ∇xJ = -dp/dt +D

C) ∇xH = J +dp/dt         D) none of these

31. Considering planes waves propagating in homogeneous non-permeable but anisotropic

dielectric, for a given wave vector k, there are ---------distinct modes of propagation

with different phase velocity satisfying Fresnel equation.

A) 2     B) 4     C) 3     D) 6

32. Poynting vector has the dimension as--------.

A) Energy B) Energy per unit area

C) Power D) Power per unit area

33. For a plane electromagnetic wave in free space which of the following relations is true

(terms have usual meaning)

A) E = E0cH    B) E = E0 H      C) H = E0cE     D) H=m0E0E

#E0= epsilon  #m0=mue

34. When an electromagnetic wave propagates through a conducting media, which among

the following statement is TRUE?

A) div E=0  B) div H ≠ 0 C) Curl H = 0 D) Curl E=0

35. A plane electromagnetic wave travels through a uniform plasma. If the Poyntings vector is

zero, then -----------.

A) frequency of the wave is greater than the plasma frequency

B) frequency of the wave is less than the plasma frequency

C) frequency of the wave and plasma frequency are equal

D) none of these

36. During reflection and refraction of electromagnetic wave, which of the following

statement is true?

A) frequency of the wave is unchanged in reflection but changes during

refraction

B) frequency of the wave is changed during reflection but unchanged during refraction

C) frequency of the wave remains unchanged during reflection and refraction

D) frequency of the wave always changes during both reflection and refraction

37. For a rectangular wave guide, -------is called the principal or dominant mode

A)TE01 B) TM01 C)TE02 D) none of these

38. In a rectangular wave guide which of the following statement is TRUE

A) TEM waves can propagate along the axis

B) TM01 mode can exist

C) The phase velocity Vg is greater than c while guide velocity Vz is less than c

D)TE01 mode cannot exist

100. The electric field intensity 􀜧 􀴤

due to an infinite uniformly charged plane sheet at a point

distant r from the sheet is related as

A) E∝r^3   B) E∝r^2   C) E∝r D) None of these

106. What is the energy of a uniformly charged spherical shell of total charge q and radius R?

B)  [q^2]/[8*pi*R]

107. The Poynting theorem is a mathematical statement of the conservation of:

A) Electromagnetic energy

B) Electromagnetic velocity

C) Electromagnetic charge

D) States

SET 2019/2

1. The total energy density of an electromagnetic wave is:

 D)    epsilon *E0^2

2. The potential at a point due to a linear quadrupole varies with distance ‘r’ as:

A) r^-1       B) r^-2         C) r^-3     D) r^3

3. The Poynting Vector of a charge q moving with a uniform velocity v is

 B) E0*(11/2)

#E0= epsilon

4. The angular frequency of electric field in an electromagnetic wave having wavelength

600 nm is 6.28x1014 rad/s. The velocity of the wave is:

A) 3x10^8 m/s B) 1.5x10^7 m/s C) 6x10^7 m/s D) 1.5x10^8 m/s

5. The vector potential at the position defined by the vector 􀝎⃗ in a uniform magnetic field is:

D) A=(1/2)*(B  X  r)

6. Divergence of position vector in three dimension ( v. r ) is

#v= dell

A) 0   B) 1  C) 2   D) 3

7. The ratio of amplitudes of magnetic and electric fields in an electromagnetic wave has

the dimension of:

A) Inductance B) Conductance C) Resistance D) Capacitance

8. The amplitudes of electric and magnetic fields in an electromagnetic wave

propagating through vacuum is related by

C) E0k=B0w

#w= omeg

9. A charged particle moves with an acceleration ‘a’. The power radiated by it is

proportional to

A) a0        B) a       C) a2        D) a3

10. The differential form of Faraday’s law of electromagnetic induction is

 B) Curl E = −m0*dH/dt

#m0= mue zero,d/dt= dou /dou t

32. A magnetic needle of moment 5x104 Am2 is suspended in a horizontal magnetic field of 4x10^-5 T. The work done to rotate it through 600 from the direction of the field is:

A) 2.0 J       B) 1 J     C) 1.2 J      D) 0.2 J

33. The phase difference between electric and magnetic fields in a plane electromagnetic wave Is:

A) 180            B) 90       C) 0     D) 45

34. The earth’s magnetic field at a point is 0.314x10-4 T. This field is to be cancelled by   magnetic field at the centre of a circular loop of radius 1 cm. The required current through the loop is:

A) 0.4 A     B) 0.5 A     C) 0.6 A       D) 0.628 A

35. Two wires of same length are shaped into a circle and square. If both of them carry same  current I, then the ratio of their magnetic moments is

A) 2 : 1         B) π : 4      C) 4 : π           D) π : 2

36. If E and B represent electric and magnetic fields of an electromagnetic wave respectively,

then which of the following is dimensionless?

 B) []B/E]*(εμ)^(1/2)

37. The dimension of ratio of magnetic flux to electric flux is

   C) L^-1T   

38. The radiation pressure exerted by an electromagnetic wave of intensity 300 mW/m2  on a non-reflecting surface in vacuum is

 B) 1x10^-9 N/m2 

40. If the horizontal component of earth’s magnetic field at a place is B0 and the dip angle is  450, then the total intensity of magnetic field at that place is

A) B0 B) 2B0 C) √2 B0 D) √2􀜤􀬴