ies - electronics engineering - electromagnetic theory qns ly

IES E & T Topic wise QuestionsElectromagnetic Theory

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YEAR 1999

MCQ 1

Consider the following operations in respect of a Wheatstone bridge :(Key Kb; is used for the supply battery and key Kg is used for the galvanometer)

1. Open Kb 2. Close Kg

3. Close Kb 4. Open Kg

The correct sequence of these operations is :

(A) 1, 2, 3, 4 (B) 3, 1, 2, 4

(C) 4, 3, 2, 1 (D) 3, 2, 4, 1

MCQ 2

The given fig. represents the variation of electric field ' 'E

IES E & T Topic wise 1999-2009 Electromagnetic Theory

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(A) due to a spherical volume charge Q Q Q1 2= +

(B) due to two concentric shells of charges Q1 and Q2 uniformly distributed over spheres of radii R1 and R2.

(C) due to two point charge Q1 and Q2 located at any two points ' 'r ( andR R1 2= )

(D) in a single spherical shell of charges Q uniformly distributed Q Q Q1 2= +

MCQ 3

Two small diameter g5 dielectric balls can slide freely on a vertical nonconducting thread. Each ball carries a negative charge of 2 C. If the lower ball is restrained from moving, then the separation between the two balls will be

(A) 8570 mm (B) 857 mm

(C) 85.7 mm (D) 8.57 mm

MCQ 4

Solution of Laplaces equation, which are continuous through the second derivative, are called

(A) Bessel functions (B) odd functions

(C) harmonic functions (D) fundamental functions

MCQ 5

Charge needed within a unit sphere centred at the origin for producing a potential field,

V r60

5

= , for r 1# is

(A) C12 (B) C60

(C) C120 (D) C180

MCQ 6

The region between two concentric conducting cylinders with radii of 2 and 5 cm contains a volume charge distribution of

10 (1 10 ) /C cmr8 3 + . If Er and V both are zero at the inner cylinder and 0 = , the potential V at the outer cylinder will be

(A) 0.506 V (B) 5.06 V

IES E & T Topicwise 1999-2009Electromagnetic Theory

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(C) 50.6 V (D) 506 V

MCQ 7

A 50 characteristic impedance line is connected to a load which shows a reflection coefficient of 0.68. If 15 VVin = , then the net power delivered to the load will be

(A) 0.139 W (B) 1.39 W

(C) 0.278 W (D) 2.78 W

MCQ 8

For a transmission line with homogeneous dielectric, the capacitance per unit length is ' 'C , the relative permittivity of the dielectric is ' 'r and velocity of light in free space is ' 'v . The characteristic impedance Z0 is equal to

(A) vCr (B)

vCr

(C) vCr (D) vC

r

MCQ 9

A dipole antenna was radiating with some excitation infree space radiating a certain amount of the power. If this antenna is immersed in a lake where water is non-magnetic and non-dissipative but has a dielectric constant of 81, the radiated power with the same excitation will

(A) decrease to finite non-zero value

(B) remain the same

(C) increase

(D) decrease to zero

MCQ 10

A TEM wave impinges obliquely on a dielectric-dielectric boundary with r 21 = and r 11 = .

The angle of incidence for total reflection is :

(A) 30c (B) 60c

(C) 45c (D) 90c


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MCQ 11

It is desired to reduce the reflected at an air porcelain by use of /4 plate. (For porcelain 0 = and 7r = ). The thickness of the

polystyrene plate required at 10 GHz will be

(A) 5.039 cm (B) 50.39 cm

(C) 0.5039 cm (D) 0.05039 cm

MCQ 12

When the phase velocity of an electromagnetic wave depends on frequency in any medium, the phenomenon is called

(A) scattering (B) polarization

(C) absorption (D) dispersion

MCQ 13

A broadside array operating at 100 cm wavelength consists of 4 half-wave dipoles spaced 50 cm apart. Each element carries radio frequency current in the same phase and of magnitude 0.5 A. The radiated power will be

(A) 146 W (B) 73 W

(C) 36.5 W (D) 18.25 W

MCQ 14

The function ( )sinF e v x vtz = satisfies the wave equation

FcF2

24 = provided

(A) v c c1 22 2

= +c m (B) ( )v c c1 /2 2 1 2 = +

(C) ( )v c c1 /2 2 1 2 = + (D v cc1 1

/

2

2 2 1 2

= +

c mMCQ 15

An antenna has a gain of 144 dB. Assuming that the main beam of the antenna is circular in cross-section, the beam width will be

(A) .0 4456c (B) .1 4456c

(C) .2 4456c (D) .3 4456c


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MCQ 16

A plane electromagnetic wave is travelling in an unbounded loss-less dielectric having 11 = and 4y = . The time average Poynting vector of the wave is 5 /W m3. The phase velocity vp (assuming velocity of light as 3 10 /m s8# ) is

(A) 1.5 10 /m s8# (B) 3 10 /m s8#

(C) 2.5 10 /m s5# (D) 0.5 10 /m s8#

MCQ 17

When a plane wave is incident normally from dielectric 1 (0, 2 ) onto dielectric 2 (0, 2 ), the electric field of the transmitted wave is 2 times the electric field of the reflected wave. The ratio /2 1 is(A) 0.5 (B) 1

(C) 2 (D) 4

MCQ 18

If for the transmission of a parallel polarized wave from a dielectric medium of permittivity 1 into a dielectric medium of permittivity 2 , there exist a value of the angle of incidence p for which the reflection coefficient is zero, then

(A) /tan h p 1 2 = (B) /tan p 1 2 =

(C) /tan p 2 1 = (D) /tan h p 2 1 =

MCQ 19

For an elliptically polarized wave incident on the interface of a dielectric at the Brewster angle, the reflected wave will be

(A) elliptically polarized

(B) linearly polarized

(C) right circularly polarized

(D) left circularly polarized

MCQ 20

A rectangular waveguide 2.29 1.02 cm# operates at a frequency of 11 GHz in TE10 mode. If the maximum potential gradient of signal is 5 /kV cm, then the maximum power handling capacity of the waveguide will be


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(A) 31.11 mW (B) 31.11 W

(C) 31.11 kW (D) 31.11 MW

MCQ 21

A cavity is a

(A) los-pass filter (B) high-pas filter

(C) band-pass filter (D) band-stop filter

MCQ 22

The amounts of time-average energies stored in electric and magnetic fields for p-th mode of a cavity resonator will be

(A) always equal

(B) equal provide the Q-factor is very high

(C) equal in the case of spherical cavities

(D) equal in the case of fundamental mode of oscillation

MCQ 23

A dipole antenna of /8 length has an equivalent total loss resistance of .1 5. The efficiency of the antenna is :

(A) 0.89159 % (B) 8.9159 %

(C) 89.159 % (D) 891.59 %

MCQ 24

For electromagnetic wave propagation in free space, the free space is defined as

(A) 0, 1, 1, 0,p j 0d ! = = = =v vY

(B) 0, 1, 1, 0,p j 0d = = = = =v v

(C) 0, 1, 1, 0,p j 0>


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(B) Both A and R are true and R is the correct explanation of A

(C) A is true but R is false

(D) A is false but R is true

MCQ 26

A quarter-wave transformer is used for matching a load of 225 ohms connected to a transmission line of 256 ohms in order to reduce the SWR along the line to 1. The characteristic impedance (in ohms) of the transformer is

(A) 225 (B) 240

(C) 256 (D) 273

MCQ 27

For distortionless transmission through a channel, the channel should be such that

(A) its attenuation response is an even function and phase response is an odd function of frequency

(B) its attenuation response is flat and phase response is linear with frequency

(C) the ratio of line inductance to line capacitance is constant

(D) its termination is by a matched impedance

MCQ 28

When VSWR is 3, the magnitude of the reflection coefficient will be

(A) 1/4 (B) 1/3

(C) 1/2 (D) 1

MCQ 29

A coaxial RF cable has the characteristic impedance of 50 and a nominal capacitance of 40 pF/m. The inductance of the cable is

(A) 1 H/m (B) 10 H/m

(C) 0.1 H/m (D) 0.0 H/m

MCQ 30

A plane wave of 10 GHz is incident normally on a dielectric plate of


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3 mm thickness. If the phase shift on transmission through the sheet is 90c, then the dielectric constant is

(A) 2.5 (B) 3.25

(C) 4.5 (D) 6.25

YEAR 2000

MCQ 31

Match List I (Laws) with List II (Application) and select the correct answer :

List-I

A. Amperes law

B. Biots law

C. Coulombs law

D. Gausss law

List-II

1. To find the force on a charge

2. To find the force due to a current carrying

3. To find the electric flux density at a point

4. To find the magnetic flux density at a point

Codes :

A B C D

(A) 3 2 4 5

(B) 3 1 2 5

(C) 4 1 2 3

(D) 4 2 5 3

MCQ 32

A solid cylindrical conductor of radius R has a uniform current density. The magnetic field H inside the conductor at a distance r from the axis of the conductor is

(A) / r1 2 (B) 1/4 r

(C) /r R1 2 2 (D) /r R1 4 2


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MCQ 33

The equation J 0 = is known as

(A) Poissons equation (B) Laplace equation

(C) Continuity equation (D) Maxwell equation

MCQ 34

A transmission line has primary constants R, L, G and C, and secondary constants Z0 and ( )jB = + . If the line is lossless, then

(A) 0, 0 0andR G! = =

(B) 0, 0 andR G \! = =

(C) 0 andG = =

(D) 0, 0, 0 andR G = = = =

MCQ 35

A transmission line having 50 impedance is terminated in a load of ( )j40 30 + . The VSWR is

(A) j0.033 (B) . .j0 8 0 6+

(C) 1 (D) 2

MCQ 36

A ( )j75 40 load is connected to a coaxial line of Z 750 = at 6 MHz. The load matching on the line can be

MCQ 37

Polystyrene has a relative permittivity of 2.7. If the wave is incident at an angle ' '1 of 30c from air onto polystyrene, the angle of transmission will be nearly

(A) .0 2c (B) 2c

(C) 18c (D) 48c

MCQ 38

Match List-I with List-II and select the correct answer using the codes given below : (Notations have their usual meaning) :

List-I List-II


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A. Permeability 1. QE

B. Force 2. /1 0 0

C. Velocity of CM wave 3. 0rD. Displacement density 4. E

Codes :

A B C D

(A) 3 2 4 5

(B) 3 1 2 5

(C) 4 1 2 3

(D) 4 2 5 3

MCQ 39

Match List-I (Antennas) with List-II (Radiation Patterns) and select the correct answer :

Codes :

A B C

(A) 1 2 3


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(B) 2 1 1

(C) 3 2 1

(D) 1 1 2

MCQ 40

A vertical wire of 1 mm length carries a current of 1 A at 10 MHz. The total radiated power is nearly

(A) 0.13 W (B) 0.88 W

(C) 7.3 W (D) 73 W

MCQ 41

A Yagi antenna has a driven antenna

(A) only (B) with a reflector

(C) with one or more directors

(D) with a reflector and one or more directors

MCQ 42

The Poynting vector P E H#= v v has the dimensions of

(A) Power/unit area (B) Volts

(C) Power (D) Volt/unit length

MCQ 43

In a hundred-turn coil, if the flux through each turn is ( )t t m23 Wb, the magnitude of the induced emf in the coil at a time of 4s is

(A) 46 mV (B) 56 mV

(C) 4.6 V (D) 5.6 V

MCQ 44

Consider the following statements regarding a plane wave propagating through free space :

The direction of field

1. E is perpendicular to the direction of propagation

2. H is perpendicular to the direction of propagation

3. E is perpendicular to the direction of field H


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Which of these statements are correct ?

(A) 1 and 2 (B) 2 and 3

(C) 1 and 3 (D) 1, 2 and 3

MCQ 45

If the velocity of electromagnetic wave in free space is 3 10 /m s8# , the velocity in a medium with r of 4.5 and r of 2 would be(A) 1 10 /m s8# (B) 3 10 /m s8#

(C) 9 10 /m s8# (D) 27 10 /m s8#

MCQ 46

Phase velocity ' 'vp and the group velocity ' 'vg in a waveguide (' 'v is a velocity of light) are related as

(A) v v cp g 2= (B) v v cp g+ =

(C) /v vp g =a constant (D) v vp g+ =a constant

MCQ 47

The cut-off wavelength c for TE20 mode for a standard rectangular waveguide is

(A) 2/a (B) 2a

(C) a (D) a2 2

MCQ 48

If 0.1 (10 ) /sin A mH t y ax8 = +v t for a place wave propagating in free space, then the time average Poynting vector is

(A) (0.6 ) /sin W my ay2 2 t (B) ( 0.6 ) /W may 2 t

(C) 1.2 /W max 2 t (D) 1.2 /W max 2 t

MCQ 49

The dimension of flux density is

(A) MT Q1 1 (B) MT Q2 2

(C) MT Q1 1 (D) MT Q1 2

MCQ 50

Assertion (A) : The solution of Poissions equation is the same as the


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solution of Laplaces equation.

Reason (R) : Laplaces equations is a special case of Poissons equation for source-free regions.

(A) Both A and R are true and R is the correct explanation of A

(B) Both A and R are true but R is NOT the correct explanation of A



YEAR 2001

MCQ 51

The energy stored per unit volume in an electric field (with usual notations) is given by

(A) / H1 2 2 (B) / E1 2

(C) / E1 2 2 (D) E 2

MCQ 52

A positive charge of Q coulomb is located at point ( , , )A 0 0 3 and a negative charge of magnetic Q coulombs is located at point ( , , )B 0 0 3. The electric field intensity at point ( , , )C 4 0 0 is in the

(A) negative x -direction (B) negative z -direction

(C) positive x -direction (D) positive z -direction

MCQ 53

The force between two points charges of 1 nC each with a 1 mm separation in air is

(A) 9 10 3# N (B) 9 10 6# N

(C) 9 10 9# N (D) 9 10 12# N

MCQ 54

A 3 F Capacitor is charged by a constant current of 2 A for 6 seconds. The voltage across the capacitor to the end of charging will be

(A) 3 V (B) 4 V


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(C) 6 V (D) 9 V

MCQ 55

Consider the following statements :

A parallel plane capacitor is filled with a dielectric of relativity r1d and connected to a d.c. voltage of V volts. If the dielectric is changed to another with relative permittivity d2= r1r1d , keeping the voltage constant, then

1. the electric field intensity E within the capacitor doubles.

2. the displacement flux density D doubles

3. the charge Q on the plates is reduced to half.

4. the energy stored in the capacitor is doubled.

Select the correct answer using the codes given below :

(A) 1 and 2 (B) 2 and 3

(C) 2 and 4 (D) 3 and 4

MCQ 56

Laplace equation in cylindrical coordinates is given by

(A) V r r rr V

r zV

zV1 1 02 2 2

2

2

2

422

22

22

22= + + =b cl m

(B) VxV

yV

zV2

2

2

2

2

2

2

422

22

22= + +

(C) V24 =

(D) sin

V r r rr V

r1 1 02

2

2 2 24 22

22

2 = + =c m

MCQ 57

Gauss law relates the electric field intensity E with the volume charge density at a point as(A) E 0# = (B) E 0: =

(C) /E 0# = (D) /E 0: =

MCQ 58

The input impedance of /8 long short-circuited section of a lossless transmission line is


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(A) zero (B) inductive

(C) capacitive (D) infinite

MCQ 59

Match List I (Parameters) with List II (Values) for a transmission line with a series impedance /mZ R j L = + and a shunt admittance

/mho mY G j C= + , and select the correct answer :

List-I List-II

A. Characteristic impedance Z0 1. ZY

B. Propagation constant 2. /Z Y

C. The sending-end input 3. /Y Z

impedance Zs when the line is terminated in its characteristic impedance Z0

Codes :

A B C

(A) 3 1 1

(B) 2 3 3

(C) 2 1 2

(D) 1 2 2

MCQ 60

A boundary separates two magnetic materials of permeability 1 and 2. The magnetic field vector in 1 and H1 with a normal component Hn1 and tangential component Ht1 while that in 2 is H2 with a normal component Hn2 and a tangential component Ht2. Then the derived conditions would be

(A) andH H H Ht t1 2 1 2= =

(B) andH H H Ht t n n1 2 1 1 2 2 = =

(C) andH H H Hn n1 2 1 1 2 2 = =

(D) , andH H H H H Ht t n n1 2 1 2 1 1 2 2 = = =

MCQ 61

For frequencies up to 1650 kHz,t he transmitting antenna used is a


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(A) parabolic dish (B) vertical antenna

(C) Yagi antenna (D) turnstile antenna

MCQ 62

The radiation field of an antenna at a distance r varies as

(A) 1/r (B) /r1 2

(C) /r1 3 (D) /r1 4

MCQ 63

The wave radiated by a helical antenna is

(A) linearly polarized

(B) right circularly polarized

(C) left circularly polarized

(D) elliptically polarized

MCQ 64

Which one of the following is NOT a correct Maxwell equation ?

(A) HtD J4# 2

2= + (B) EtH

4# 22=

(C) D4: = (D) B 04: =

MCQ 65

In a certain microstrip path antenna, the unexcited patch is of length L , width W , thickness of the substrate being h and its relative permittivity r . Then, the capacitance of the unexcited patch is

(A) /LW hr (B) /LW hr0

(C) /LW hr (D) /LW hr0

MCQ 66

Match List I (Maxwell equation) with List II (Description) and select the correct answer :

List I

A. B da 0: =v v#


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B. D da dVV

: =v v ##

C. E ds Bda: =v v ##

D. ( )H ds D J da: := +v v ##List II

1. The mmf around a closed path is equal to the conduction current plus the time derivative of the electric displacement current through any surface bounded by the path.

2. The emf around a closed path is equal to the time derivative is equal to the time derivative of the magnetic displacement through any surface bounded by the path.

3. The total electric displacement through the surface enclosing a volume is equal to total charge within the volume

4. The net magnetic flux emerging through any closed surface is zero.

Codes :

A B C D

(A) 1 3 2 4

(B) 4 3 2 1

(C) 4 2 3 1

(D) 1 2 3 4

MCQ 67

In a uniform plane wave, the value of /E H is

(A) / (B) /

(C) 1 (D)

MCQ 68

For a hollow waveguide, the axial current must necessarily be

(A) a combination of conduction and displacement currents

(B) time-varying conduction current and displacement current

(C) time-varying conduction current and displacement current

(D) displacement current only


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MCQ 69

A cylindrical cavity resonates at 9 GHz in the TE111 mode. The bandwidth 3 dB is measured to be 2.4 MHz. The Q of the cavity at 9 GHz is

(A) / .9000 2 4 3 (B) / .9000 2 4 2

(C) . /9000 2 4 3 2# (D) / .9000 2 4

MCQ 70

The phenomenon of microwave signals following the curvature of earth is known as

(A) Faraday effect (B) ducting

(C) wave tilt (D) troposcatter

MCQ 71

A radio communication link is to be established via the ionosphere. The virtual height at the mid-point of the path is 300 km and the critical frequency is 9 MHz. The maximum usable frequency for the link between the stations of distance 800 km assuming flat earth is

(A) 11.25 MHz (B) 12 MHz

(C) 15 MHz (D) 25.5 MHz

MCQ 72

Which one of the following statements is NOT correct for a plane wave with 0.5 (10 2 ) /cos A mH e t x a. x z0 1 6= t

(A) The wave frequency is 106 r.p.s

(B) The wavelength is 3.14 m

(C) The wave travels along + x -direction

(D) The wave is polarized in the z -direction

MCQ 73

A coil of resistance of 5 and inductance 0.4 H is connected to a 50 V d.c. supply. The energy stored in the field is

(A) 10 joules (B) 20 joules

(C) 40 joules (D) 80 joules


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MCQ 74

Assertion (A) : Programmes broadcast by radio stations operating in the medium wave band of 550 to 1650 kHz situated at long distance in excess of 500 km cannot be heard during day-time but may be heard during night time.

Reason (R) : In the night-time, radio waves reflected from the F-layer suffer negligible attenuation since D-and E-layers are absent during the night-time.

(A) Both A and B are true and R is the correct explanation of A

(B) Both A and R are true and but R is NOT the correct explanation of A



MCQ 75

Assertion (A) : For an end-fire array, the current in successive antennas must lag in phase.

Reason (R) : Radiation of successive antennas will cancel along the axis.





MCQ 76

Assertion (A) : The radio horizon for space wave is more than the optical horizon.

Reason (R) : The atmosphere has varying density.






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MCQ 77

Which of the following conditions will not guarantee a distortionless transmission line ?

(A) R G 0= =

(B) RC GL=

(C) Very low frequency range ( , )R L G C>> >>

(D) Very high frequency range ( , )R L G C


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effect.

(A) Both A and R are true R is the correct explanation of A

(B) Both A and R are true R is NOT the correct explanation of A



MCQ 81

Assertion (A) : For an E.M. wave normally incident on a conductor surface the magnetic on a conductor surface the magnetic field H undergoes a 180c phase reversal and the phase of electric field E remains same.

Reason (R) : The direction of propagation of incident wave will reverse after striking a conductor surface.





MCQ 82

Assertion (A) : A /4 short circuited line behaves as a series resonant circuit.

Reason (R) : At a particular frequency the input impedance becomes infinite.


(B) Both A and R is true but R is NOT the correct explanation of A



MCQ 83

A field ( )A x yza x za x y z a3 2x y z2 3 3= + + can be termed as(A) Harmonic (B) Divergence less

(C) Solenoidal (D) Rotational

MCQ 84


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Consider the following :

For a lossless transmission line we can write :

1. Z jZin 0= for a shorted line with /1 8=

2. Z jin ! \= for a shorted line with /4=

3. Z Zin 0= for a matched line of any length

Select the correct answer using the codes given below :

(A) 1 and 2 (B) 2 and 3

(C) 1 and 3 (D) 2 and 4

MCQ 85

The input impedance of a short circuited quarter wave long transmission lien is

(A) purely reactive

(B) purely resistive

(C) dependent on the characteristic impedance of the line

(D) none of the above

MCQ 86

The current distribution along a travelling wave antenna can be written in the form

(A) Z e j z0

= (B) ( ) sinZ z0=

(C) ( )Z0

= (D) ( ) ( )cosZ t z0

=

MCQ 87

Match List I with List II and select the correct answer :

List-I

A. Propagation constant

B. Radiation intensity

C. Wave impedance

List-II

1. /2

2. / ( )r h E22 2

3. /E Ht t


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4. E H#v v

Codes :

A B C

(A) 1 2 3

(B) 4 3 2

(C) 1 3 2

(D) 4 2 3

MCQ 88

For a wave propagation in an air filled rectangular waveguide.

(A) guided wavelength is never less than free space wavelength

(B) wave impedance is never less than the free space impedance

(C) TEM mode is possible if the dimensions of the waveguide are properly chosen

(D) Propagation constant is always a real quantity

MCQ 89

Consider the following statements with reference of Brewster angle :

1. For oblique incidence at a boundary, there is no reflected wave is vertically polarzed.

2. Brewstar angle can occur only at the boundary of a perfect conductor.

3. For a horizontally polarized wave, there is no Brewster angle.

4. When the incident wave is not fully vertically polarized, there will be a reflected component which is horizontally polarized.


(A) 1, 2 and 3 (B) 2, 3 and 4

(C) 3, 4 and 1 (D) 4, 1 and 2

MCQ 90


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The circulation of Hv around the closed contour C , shown in the fig. is :

(A) 0 (B) 2l

(C) 4l (D) 6l

MCQ 91

A transmission line of output impedance 400 is to be matched to a load of 25 through a quarter wavelength line. The quarter wave line characteristic impedance must be

(A) 40 (B) 100

(C) 400 (D) 425

MCQ 92

If the Ev field of a plane polarized e.m. wave travelling in the Z-direction is :

E a E a Ex x y y= +v v v then its Hv direction is :

(A) a ZE a Z

Ey

xx

y

0 0v v (B) a Z

E a ZE

yx

xy

0 0+v v

(C) a ZE

a ZE

xy

yx

0 0v v (D) a Z

Ea ZE

xy

yx

0 0 v v

MCQ 93

A dipole produces an electric field intensity of 1 /mV m at a distance of 2 km. The field intensity at a distance of 4 km will be

(A) 1 mv/m (B) 0.75 mv/m

(C) 0.50 mv/m (D) 0.25 mv/m

MCQ 94

Following antenna is frequently used for local are transmission at


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UHF/VHF

(A) Ground monopole (B) Turnstile antenna

(C) Slot antenna (D) Loop antenna

MCQ 95

Consider the following statements :

For electromagnetic waves propagating in free space :

1. electrical field is perpendicular to direction of propagation

2. electrical field is along the direction of propagation

3. magnetic field is perpendicular to direction of propagation

4. magnetic field is along the direction of propagation


(A) 1 and 3 (B) 1 and 4

(C) 2 and 3 (D) 2 and 4

MCQ 96

When a particular mode is excited in a wave-guide, there appears an extra electric component in the direction of propagation.

The resulting mode is

(A) transverse-electric

(B) transverse-magnetic

(C) longitudinal

(D) transverse-electromagnetic

MCQ 97

A lossless transmission line is connected to two identical voltage source as shown in the fig.


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The impedance measured at the mid point AA of the line is

(A) \ (B) 100

(C) 50 (D) 25

MCQ 98

The vector length of the curve cos2 = (Cylindrical Co-ordinates) from 0 = to = is

(A) 0.5 (B) 1.0

(C) 2.0 (D)

YEAR 2003

MCQ 99

An electric charge Q is placed in a dielectric medium. Which of the following quantities are independent of the dielectric constant of the medium ?

(A) Electric potential V and Electric field intensity E

(B) Displacement density D and Displacement

(C) Electric field intensity E and Displacement density D

(D) Electric potential V and Displacement

MCQ 100

Two coaxial cylindrical sheets of charge are present in free space, 5 /C ms 2 = at 2 mr = and 2 /C mrs 2= at 4 mr = . The displacement

flux density D at 3 mr = is

(A) 5 /C mD ar 2= (B) 2/3 /C mD ar 2=

(C) 10/3 /C mD ar 2= (D) 18/3 /C mD ar 2=

MCQ 101

Two thin parallel wires are carrying current along the same direction. The force experienced by one due to the other is

(A) Parallel to the lines

(B) Perpendicular to the lines and attractive

(C) Perpendicular to the lines and repulsive

(D) Zero


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MCQ 102

An electric potential field is produced in air by point charge 1 C and 4 C located at ( , , )1 1 5 and ( , , )1 3 1 respectively. The energy stored in the field is

(A) 2.57 mJ (B) 5.14 mJ

(C) 10.28 mJ (D) 12.50 mJ

MCQ 103

Which one of the following potentials does NOT satisfy Laplaces Equation ?

(A) V xy10= (B) cosV R =

(C) /V r10= (D) cosV 10 = +

MCQ 104

Laplacian of a scalar function V is

(A) Gradient of V (B) Divergence of V

(C) Gradient of the gradient of V (D) Divergence of the gradient of V

MCQ 105

Match List I (Dominant Mode of Propagation) with List II (Type of transmission Structure) and select the correct answer :

List-I List-II

A. Coaxial line 1. TE

B. Rectangular waveguide 2. Quasi TEM

C. Microstrip line 3. Hybrid

D. Coplanar waveguide 4. TEM

Codes :

A B C D

(A) 1 4 2 3

(B) 4 1 3 2

(C) 1 4 3 2

(D) 4 1 2 3


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MCQ 106

In a line VSWR of a load is 6 dB. The reflection coefficient will be

(A) 0.033 (B) 0.33

(C) 0.66 (D) 3.3

MCQ 107

Z 200L = and it is desired that Z 50i = . The quarterwave transformer should have a characteristic impedance of

(A) 100 (B) 40

(C) 10,000 (D) 4

MCQ 108

A TEM wave impinges obliguely on a dielectric-dielectric boundary (,r r2 11 2 = = ). The angle of incidence for total reflection is

(A) 30c (B) 45c

(C) 60c (D) 75c

MCQ 109

A plane electromagnetic wave travelling in a perfect dielectric medium of characteristic impedance 1 is incident normally on its impedance with another perfect dielectric medium of characteristic impedance

2 . The electric and magnetic field strengths of the incident wave are denoted by andE H1 1 respectively whereas andE Hr r denote these quantities for the reflected wave, and andE Ht t for the transmitted wave.

Which of the following relations are correct ?

1. E Hi i1=

2. E Hr r1=

3. E Ht t2=

Select the correct answer using the codes given below

(A) 1, 2 and 3 (B) 1 and 2

(C) 1 and 3 (D) 2 and 3

MCQ 110

A plane electromagnetic wave travelling in a perfect dielectric medium


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of dielectric constant 1 is incident on its boundary with another perfect dielectric medium of dielectric constant 2 . The incident ray makes an angle of 1 with the normal to the boundary surface. The ray transmitted into the other medium makes an angle of 2 with the normal.

If 2 60and1 2 1 c = = , which one of the following is correct ?(A) 452 c =

(B) .sin 0 4332 1 =

(C) .sinq 0 6122 1=

(D) There will be no transmitted wave

MCQ 111

In a four element Yagi-Uda antenna

(A) There is one driven element, one director and two reflectors

(A) There is one driven element, two directors and one reflector

(C) There are two driven elements, one director and two reflectors

(D) All the four elements are driven elements

MCQ 112

Which one of the following Maxwells equations gives the basic idea of radiation ?

(A) /

/

H D t

E B t

2 2

2 2

#

#

== 4 (B)

/

/

E B t

D B t:

2 2

2 2

# =

= 4(C)

D

D 0

:

:

==

3 (D) ( / )

B

H D t

:

# 2 2

== 4

MCQ 113

For orTE TM modes of propagation in bounded media, the phase velocity

(A) is independent of frequency

(B) is a linear function of frequency

(C) is a non-linear function of frequency

(D) Can be frequency-dependent or frequency-independent depending on the source

MCQ 114


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A waveguide operated below cut-off frequency can be used as

(A) A phase shifter

(B) An attenuator

(C) An isolator

(D) None of the above

MCQ 115

Match List I (Nature of Polarization) with List II (Relationship Between andX Y Components) for a propagating wave having cross-section in the XY plane and propagating along Z -direction and select the correct answer :

List-I

A. Linear

B. Left circular

C. Right circular

D. Elliptical

List-II

1. andX Y components are in same phase

2. andX Y components have arbitrary phase difference

3. X component leads Y by 90c

4. X component lags behind Y by 90cCodes :

A B C D

(A) 1 4 2 3

(B) 4 1 2 3

(C) 1 4 3 2

(D) 4 1 3 2

MCQ 116

An air condenser of capacitance of 0.005 F is connected to a d.c. supply of 500 Volts, disconnected and then immersed in oil with a dielectric constant of 2.5. Energy stored in the capacitor before and after immersion, respectively is

(A) 500 10 250 10andJ J4 4# #


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(B) 250 10 500 10andJ J4 4# #

(C) 10 10andJ J625 2504 4# #

(D) 250 10 10andJ J6254 4# #

MCQ 117

Assertion (A) : For extremely high frequency ranges or above, compared to linear antennas, aperture antennas are more useful.

Reason (R) : The larger the effective area of an antenna, the sharper is the radiated beam.





MCQ 118

Assertion (A) : The quality factor Q of a waveguide is closely related to its attenuation factor .

Reason (R) : Normally attenuation factors obtainable in waveguides are much higher than those obtainable in transmission lines.




(D) A is false but R is

YEAR 2004

MCQ 119

Which one of the following statements is correct ?

A right circularly polarised wave is incident from air onto a polystyrene ( .2 7r = ). The reflected wave is(A) right circularly polarised

(B) left circularly polarised

(C) right elliptically polarised


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(D) left elliptically polarised

MCQ 120

A point charge of 10 C+ placed at a distance of 5 cm from the centre of a conducting grounded sphere of radius 2 cm is shown in the diagram given below :

What is the total induced charge on the conducting sphere ?

(A) 10 C (B) 4 C

(C) 5 C (D) 12.5 C

MCQ 121

For sea water with 5 /mho m = and 80r = , what is the distance for which radio signal can be transmitted with 90% attenuation at 25 kHz ?

(A) 0.322 m (B) 3.22 m

(C) 32.2 m (D) 322 m

MCQ 122

Two metal rings 1 and 2 are placed in a uniform magnetic field which is decreasing with time with their planes perpendicular to the field. If the rings are identical except that ring 2 has a thin air gap in it, which one of the following statements is correct ?

(A) No e.m.f is induced in ring 1

(B) An e.m.f is induced in both the rings

(C) Equal Joule heating occurs in both the rings

(D) Joule heating does not occur in either ring.

MCQ 123

The electric field of a wave propagating through a lossless medium


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( , )810 0 is ( )cosE t bx a10 6 10 y8#=

What is the phase constant of the wave ?

(A) 2 /rad m (B) 9 /rad m

(C) 18 /rad m (D) 81 /rad m

MCQ 124

Which one of the following gives the values of the attenuation factor and phase shift factor for a wave propagated in a good dielectric having /( ) 1>> ?

(A) [ / ]

;2 = = (B) / ; / = =

(C) [ / ]

;2 = = (D) ,0 2 = =

MCQ 125

If the phase velocity of a plane wave in a perfect dielectric is 0.4 times its value in free space, then what is the relative permittivity of the dielectric ?

(A) 6.25 (B) 4.25

(C) 2.5 (D) 1.25

MCQ 126

In free space ( , ) 60( 2 ) /V mE x t t x ay= . What is the average power crossing power crossing a circular area of radius 4 m in the plane

tancons tx = ?

(A) 480 W (B) 340 W

(C) 120 W (D) 60 W

MCQ 127

Consider the following statements regarding Smith charts :

1. A normalized Smith chart applies to a line of any characteristic resistance and serves as well for normalized admittance

2. A polar coordinate Smith chart contains circles of constant z and circles of constant z+

3. In Smith chart, the distance towards the load is always measured in clockwise direction.


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Which of the statements given above are correct ?

(A) 1, 2 and 3 (B) 2 and 3

(C) 1 and 3 (D) 1 and 2

MCQ 128

A j100 75 ^ h load is connected to a co-axial cable of characteristic impedance 75 ohms at 12 GHz. In order to obtain the best matching, which one of the following will have to be connected ?

(A) A short-circuited sub at load

(B) Inductance at load

(C) A capacitance at a specific distance at load

(D) A short-circuited stub at some specific distance from load

MCQ 129

What is the effect of the earths magnetic field in the reflected wave at frequencies in the vicinity of gyro-frequency ?

(A) No attenuation in the reflected wave

(B) Decreased attenuation in the reflected wave

(C) Increased attenuation in the reflected wave

(D) Nominal attenuation in the reflected wave

MCQ 130

Consider the following statements relating to the cavity resonators :

1. For over-coupling the cavity terminals are at voltage maximum in the input line at resonance

2. For over-coupling the cavity terminals are at the voltage minimum in the input line at resonance

3. For under-coupling the normalized impedance at the voltage maximum is the standing wave ratio

4. For over-coupling the input terminal impedance is equal to the reciprocal of the standing wave ratio

Which of the statements given above are correct ?

(A) 1 and 2 (B) 3 and 4

(C) 1 and 3 (D) 2 and 4


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MCQ 131

Which one of the following statements is correct ? Short-circuited stubs are preferred to open-circuited stubs are preferred to open-circuited stub because the later are

(A) more difficult to make and connect

(B) made of a transmission line with a different characteristic impedance

(C) liable to radiate energy

(D) incapable of giving a full range of frequencies

MCQ 132

Which one of the following statements is correct ?

An antenna array consists of 5 omni-directional elements carrying equal in-phase currents. The elements are equally spaced along x-axis with the spacing between adjacent elements being equal to one wavelength. The directivity pattern will have a maximum.

(A) only in x -direction

(B) only in y -direction

(C) both x -and y -direction

(D) in the direction making an angle of 45c with x -axis.

MCQ 133

Match List I (Characteristic to be Obtained) with List II (Arrangement of Radiators) and select the correct answer using the codes given below :

List-I

A. Concentration of radiation in azimuth

B. Concentration of radiation in elevation

C. Bi-directional pattern

List-II

1. Two radiators spaced /3 4 apart and fed with currents having 180c phase difference

2. Two radiators spaced /4 apart and fed with currents having 180c phase difference


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3. Radiators arranged to form broadside array with horizontal array line

4. Radiators arranged to form broadside array with vertical array line

Codes :

A B C

(A) 2 4 3

(B) 3 4 2

(C) 3 1 2

(D) 2 1 3

MCQ 134

Consider the following statements relating to the microstrip lines :

1. Modes on microstrip lines are purely TEM

2. Microstrip line is also called open strip line

3. Radiation loss in microstrip line can be reduced by using thin high dielectric materials

4. Conformal transformation technique is quite suitable for solving microstrip problems

Which of the following given above are correct ?

(A) 1, 2 and 3 (B) 2, 3 and 4

(C) 1, 3 and 4 (D) 1, 2 and 4

MCQ 135

An infinitely long uniform charge of density 30 nC/m is located at ,y z3 5= = . The field intensity at (0, 6, 1) is 64.7 86.3 /V mE a ay z=

. What is the field intensity at ( , , )5 6 1 ?

(A) E (B) E5 6 1

6 12 2 2

2 2

+ ++c m

(C) E5 6 1

6 1 /2 2 2

2 2 1 2

+ ++c m (D) E6 15 6 1

/

2 2

2 2 2 1 2

++ +c m

MCQ 136

What is the magnetic dipole moment in Am2 for a square current loop having the vertices at the point (10,0,0), (0,10,0), ( 10,0,0)A B C and


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(0, 10,0)D and with current 0.01 A flowing in the sense ABCDA ?(A) a2 z (B) a2 z

(C) a4 z (D) ( )a a4 x y+

MCQ 137

For an electric field sinE E t0 = , what is the phase difference between the conduction current and the displacement current ?

(A) 0c (B) 45c

(C) 90c (D) 180c

MCQ 138

An infinitely long line charge of uniform charge density /C m0 is situated parallel to and at a distance from the grounded infinite plane conductor. This field problem can be solved by which one of the following ?

(A) By conformal transformation

(B) By method of images

(C) By Laplaces equation

(D) By Poissons equation

YEAR 2005

MCQ 139

The capacitance of a parallel plate capacitor is given by r0 (A/d) where A is the area of each plates. Considering fringing between the plates. Considering fringing field, under which one of the following conditions is the above expression valid ?

(A) dA is tending towards zero

(B) dA is tending towards infinity

(C) dA is 1

(D) dA is 1

r 0

MCQ 140


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Current density ( )jv , in cylindrical co-ordinate system is given as :

( , , )J r z 0= for r a0 < < ( / )J r a I z0 2= v for a r b< >0= 2. ,lnR a

b b a4 >>0 b l

3. ( / )lnR b a20 = 4. ,lnR a

b b a2 >>0 = b l

Codes :


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A B C D

(A) 3 4 1 2

(B) 2 1 4 3

(C) 3 1 4 2

(D) 2 4 1 3

MCQ 196

A broadside array of four isotropic point sources of same amplitude and phase, placed along x axis with a spacing of /2 between adjacent elements has a polar pattern consisting of which of the following ?

(A) One major lobe in the +ve y -direction and one major lobe in the negative y direction and no side lobes

(B) One major lobe in the +ve y -direction, one major lobe in the negative y -direction, one minor lobe in the +ve x -direction and one minor lobe in the ve direction

(C) One major lobe in the +ve y -direction one major lobe in the negative y -direction, one minor lobe in each of the four quadrants

(D) Four major lobes one each in ; ; andy y x x+ + directions and no other side lobes

MCQ 197

Which one of the following is correct ? Normal mode helical antenna has

(A) low radiation efficiency and high directive gain

(B) high radiation efficiency and low directive gain

(C) low radiation efficiency and low directive gain

(D) high radiation efficiency and high directive gain

MCQ 198

A radio frequency signal at a frequency 1000 kHz is to be received by using reflection from ionoshpere. When is it possible ?

(A) At daytime only

(B) By using a launch angle 60> c to normal

(C) If high power is used

(D) When frequency is low for broadcast use


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MCQ 199

If the reflection coefficient is 1/5, what is the corresponding VSWR ?

(A) 3/2 (B) 2/3

(C) 5/2 (D) 2/5

MCQ 200

For taking antenna far field pattern, what must be the distance R , between transmitting and receiving antennas ?

(A) R D2>2

(B) RD3

4>2 2

(C) R D2

> 22

(D) R D2> 2

2

MCQ 201

A transmitting antenna has a gain of 10. It is fed with a signal power of 1 W. Assuming free-space propagation, what power would be captured by a receiving antenna of effective area 1 m2 in the bore sight direction at a distance of 1 m ?

(A) 10 W (B) 1 W

(C) 2 W (D) 0.8 W

MCQ 202

What must be angle of a corner reflector, such that an incident wave is reflected in the same direction ?

(A) 30c (B) 45c

(C) 60c (D) 90c

MCQ 203


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The hybrid T is ideal, perfectly matched on all ports. The VSWR at the input is

(A) 2.0 (B) 2.5

(C) 3.0 (D) 3.5

MCQ 204

The Fraunhofer region where the pattern measurement of transmitting

antenna has to be taken is form a distance of 2D , where D is the

maximum aperture dimension and is the free-space wavelength. What is the region generally known as ?

(A) The near field

(B) The far field

(C) Quiet zone

(D) Induction field

MCQ 205

Poynting vector is a measure of which one of the following ?

(A) Maximum power flow through a surface surrounding the source

(B) Average power flow through the surface

(C) Instantaneous power flow through the surface

(D) Power dissipated by the surface

MCQ 206

Why is delay distortion in coaxial cables caused ?

(A) The dielectric constant ( )r of the dielectric filling the coaxial cable varies with frequency

(B) The amplitude of the signal on the cable varies with frequency

(C) The velocity of electromagnetic waves propagating on the cable varies with frequency


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(D) Because of both factor given at (A) and (C) above

YEAR 2008

MCQ 207

The line integral of the vector potential A around the boundary of a surface S represents which one of the following?

(A) Flux through the surface S

(B) Flux density in the surface S

(C) Magnetic field intensity

(D) Current density

MCQ 208

What is the electric flux density ( / )in C m2 at a point ( , , )6 4 5 caused by a uniform surface charge density of 60 /C m2 at a plane x 8= ?

(A) a30 x (B) a60 x

(C) a30 x (D) a60 x

MCQ 209

An infinitely long straight conductor located along z-axis carries a current I in the +ve z -direction. The magnetic field at any point P in the x y plane is in which direction?

(A) In the positive z -direction

(B) In the negative z -direction

(C) In the direction perpendicular to the radial line OP (in x y plane) joining the origin O to the point P

(D) Along the radial line OP

MCQ 210

A 5 A current enters a right circular cylinder of 5 cm radius. What is the linear surface current density at the end surface?

(A) (50/ ) /A m (B) (100/ ) /A m

(C) (1000/ ) /A m (D) (2000/ ) /A m


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MCQ 211

Of two concentric long conducting cylinders, the inner one is kept at a constant positive potential V0+ and the outer one is grounded. What is the electric field in the space between the cylinders?

(A) Uniform and directed radially outwards

(B) Uniform and directed radially inwards

(C) Non-uniform and directed radially outwards

(D) Non-uniform and directed parallel to the axis of the cylinders

MCQ 212

In a charge free space, the Poissons equation results in which one of the following?

(A) Continuity equation (B) Maxwells equation

(C) Laplace equation (D) None of the above

MCQ 213

A lossless transmission line of characteristic impedance Z0 and length /l 4< is terminated at the load end by an open circuit. What is its

input impedance Zs?

(A) tanZ jZ ls 0 = (B) cotZ jZ ls 0 =

(C) tanZ jZ ls 0 = (D) tanZ jZ ls 0 =

MCQ 214

Consider the following statements associated with boundary conditions between two media:

1. Normal component of B is continuous at the surface of discontinuity.

2. Normal component of D may or may not be continuous.

Which of the statement(s) given above is/are correct?(A) 1 only (B) 2 only

(C) Both 1 and 2 (D) Neither 1 nor 2

MCQ 215

According to Poynting theorem, the vector product E H#v v is a measure of which one of the following?


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(A) Stored energy density of the electric field

(B) Stored energy density of the magnetic

(D) Power dissipated per unit volume

(E) Rate of energy flow per unit area

MCQ 216

If the total input power to an antenna is Wt , the radiated power is Wr, and the radiation intensity is , then match List-I with List-II and select the correct answer using the code given below the lists:

List-I

A. Power gain

B. Directive gain

C. Average power radiated

D. Efficiency of the antenna

List-II

1. /W Wr t 2. /W 4r

3. /W4 t 4. /W4 r

Codes :

A B C D

(A) 3 4 2 1

(B) 4 3 2 1

(C) 3 4 1 2

(D) 4 3 1 2

MCQ 217

Where does the maximum radiation for an end-fire array occur?

(A) Perpendicular to the line of the array only

(B) Along the line of the array

(C) AT 45c to the line of the array

(D) Both perpendicular to and along the line of the array

MCQ 218


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As the aperture area of an antenna increases, its gain

(A) increases (B) decreases

(C) remains steady (D) behaves unpredictably

MCQ 219

Inside a waveguide with perfectly conducting walls, any current present is in the form of

(A) displacement current only

(B) conduction current only

(C) partially displacement current and partially conduction current

(D) sometimes displacement current and sometimes conduction current

MCQ 220

What is the unit of measurement of surface/sheet resistivity?

(A) Ohm/metre (B) Ohm metre

(C) Ohm/sq. meter (D) Ohm

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