# Multiple choice question for engineering

## Set 1

1. The resonant circuit in a waveguide refers to the

a) Tank circuit

b) RC circuit

c) Bridge circuit

d) Attenuator circuit

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2. When a waveguide is terminated, the mode of the guided termination will be

a) zero

b) non-zero

c) infinite

d) does not exist

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3. The cut off frequency of a waveguide with resonant cavity is given by

a) V√((m/a)^{2} + (n/b)^{2} + (p/d)^{2})/2

b) V√((m/a)^{2} + (n/b)^{2} + (p/d)^{2})

c) 2V√((m/a)^{2} + (n/b)^{2} + (p/d)^{2})

d) V√((m/a) + (n/b) + (p/d))/2

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^{2}+ (n/b)

^{2}+ (p/d)

^{2})/2. Here m and n are the orders of the waveguide, p is the order of the cavity and v is the velocity.

4. The power of a wave in a transmission line, when the current and the resistance are 5A and 120 ohm respectively is

a) 3000

b) 4000

c) 2000

d) 1500

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^{2}R. On substituting for I = 5 and R = 120, we get P = 5

^{2}x 120 = 3000 units.

5. The power of a wave having a magnetic field intensity of 2.5 units is

a) 1.17 kilo watt

b) 1.17 mega watt

c) 1.17 watt

d) 11.7 watt

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^{2}, where η is the intrinsic impedance and H is the magnetic field intensity. On substituting for η = 377 and H = 2.5, we get P = 0.5 x 377 x 2.5

^{2}= 1.17 kilo watts.

6. The power of a wave having an electric field strength of 12.8 units is

a) 0.217

b) 0.721

c) 0.127

d) 0.172

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^{2}/η, where E is the electric field intensity and η is the intrinsic impedance. On substituting for E = 12.8 and η = 377, we get P = 0.5 x 12.8

^{2}/377 = 0.217 units.

7. The form or mode of propagation is determined by which factors?

a) Type of excitation device

b) Location of excitation device

c) Type and location of the excitation device

d) Waveguide characteristics

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8. The phase of the wave after the installation of the guided terminations will be

a) 0

b) 45

c) 90

d) 180

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9. The exciter of the waveguide in a transmission line is the

a) Transmitter

b) Receiver

c) Transponder

d) Antenna

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10. A waveguide imitates which type of filter characteristics?

a) Low pass filter

b) High pass filter

c) Band pass filter

d) Band reject filter

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## Set 2

1. Which of the following parameters does not exist in the transmission line equation?

a) R

b) Zo

c) ZL

d) Propagation constant

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2. For an infinite transmission line, the characteristic impedance is given by 50 ohm. Find the input impedance.

a) 25

b) 100

c) 2500

d) 50

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3. The best transmission length for effective transmission of power is

a) L = λ/4

b) L = λ/8

c) L = λ/2

d) L = ∞

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4. When the length of the transmission line is same as that of the wavelength, then which condition holds good?

a) Zin = Zo

b) Z = Zo

c) ZL = Zo

d) Zin = ZL

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5. The input impedance of a half wave transmission line with a load impedance of 12.5 ohm is

a) 25

b) 50

c) 6.25

d) 12.5

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6. The condition for a quarter wave transformer is

a) Zo^{2} = Zin ZL

b) Zo = Zin ZL

c) ZL^{2} = Zin Zo

d) Zo = Zin

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^{2}= Zin ZL is the required condition.

7. Find the characteristic impedance of a quarter wave with input and load impedances given by 50 and 25 respectively.

a) 50

b) 25

c) 75

d) 35.35

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^{2}= Zin ZL. On substituting for Zin = 50 and ZL = 25, we get Zo

^{2}= 50 x 25. The characteristic impedance will be 35.35 ohm.

8. Find the load impedance in a quarter line transformer with characteristic impedance of 75 ohm and input impedance of 200 ohm.

a) 28.125

b) 12.285

c) 52.185

d) 85.128

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^{2}= Zin ZL. On substituting for Zo = 75 and Zin = 200, we get ZL = Zo

^{2}/Zin = 75

^{2}/200 = 28.125 ohm.

9. The reflection coefficient of a perfectly matched transmission line is

a) 1

b) -1

c) 0

d) ∞

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10. The purpose of the transmission line equation is to

a) Find primary parameters

b) Find secondary parameters

c) Find the reflection cofficient

d) Impedance matching

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11. The quarter wave transformer can be considered as a

a) Impedance inverter

b) Impedance doubler

c) Impedance tripler

d) Impedance quadrupler

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12. Which transmission line is called as one to one transformer?

a) L = λ

b) L = λ/2

c) L = λ/4

d) L = λ/8

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## Set 3

1. Which of the following parameters is not a primary parameter?

a) Resistance

b) Attenuation constant

c) Capacitance

d) Conductance

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2. The networks in which the R, L, C parameters are individually concentrated or lumped at discrete points in the circuit are called

a) Lumped

b) Distributed

c) Parallel

d) Paired

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3. The lines having R, L, C distributed along the circuit are called

a) Lumped

b) Distributed

c) Parallel

d) Paired

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4. Which primary parameter is uniformly distributed along the length of the conductor?

a) G

b) C

c) L

d) R

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5. The primary parameter that is associated with the magnetic flux linkage is

a) R

b) L

c) C

d) G

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6. The primary parameter that is associated with the electric charges is

a) G

b) R

c) C

d) L

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7. The leakage current in the transmission lines is referred to as the

a) Resistance

b) Radiation

c) Conductance

d) Polarisation

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8. Find the receiving impedance of a transmission line having a voltage of 24V and a conduction current of 1.2A is

a) 25.2

b) 22.8

c) 28.8

d) 20

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9. The characteristic impedance of a transmission line with impedance and admittance of 16 and 9 respectively is

a) 25

b) 1.33

c) 7

d) 0.75

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10. The propagation constant of a transmission line with impedance and admittance of 9 and 16 respectively is

a) 25

b) 144

c) 12

d) 7

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11. Find the characteristic impedance expression in terms of the inductance and capacitance parameters.

a) Zo = √(LC)

b) Zo = LC

c) Zo = √(L/C)

d) Zo = L/C

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12. When a transmission line has a load impedance same as that of the characteristic impedance, the line is said to be

a) Parallel

b) Perpendicular

c) Polarized

d) Matched

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## Set 4

1. In transverse magnetic waves, which of the following is true?

a) E is parallel to H

b) H is parallel to wave direction

c) H is transverse to wave direction

d) E is transverse to H

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2. The dominant mode in the TM waves is

a) TM_{01}

b) TM_{10}

c) TM_{20}

d) TM_{11}

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_{10}, TM

_{01}and TM

_{20}does not exist in any waveguide. The TM

_{11}mode is the dominant mode in the waveguide.

3. The modes in a waveguide having a V number of 20 is

a) 400

b) 200

c) 100

d) 40

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^{2}/2. On substituting for V = 20, we get m = 400/2 = 200 modes.

4. The v number of a waveguide having 120 modes is

a) 15.5

b) 18

c) 24

d) 12

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^{2}/2. On substituting for m = 120, we get V = √(2 x 120) = 15.5.

5. The intrinsic impedance of a TM wave will be

a) Greater than 377 ohm

b) Equal to 377 ohm

c) Lesser than 377 ohm

d) Does not exist

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_{TM}= η √(1-(fc/f)

^{2}). Here the term √(1-(fc/f)

^{2}) is always lesser than unity. Thus the intrinsic impedance of the TM wave is lesser than 377 ohms.

6. The modes TM_{mo} and TM_{on} are called

a) Generate modes

b) Degenerate modes

c) Dominant modes

d) Evanescent modes

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_{mo}and TM

_{on}does not exist. These modes are said to be evanescent mode.

7. Two modes with same cut off frequency are said to be

a) Generate modes

b) Dominant modes

c) Degenerate modes

d) Regenerate modes

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8. Does the mode TM_{30} exists?

a) Yes

b) No

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_{mo}and TM

_{on}does not exist. The given mode is in the form of TM

_{mo}, which is does not exist. It is an evanescent mode.

9. The boundary between the Fresnel and Fraunhofer zones having a length of 12 units and a wavelength of 3 units is

a) 96

b) 48

c) 192

d) 36

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^{2}/λ. On substituting for L = 12 and λ = 3, we get R = 2 x 12

^{2}/3 = 96 units.

10. The reflection coefficient, when a resonant cavity is placed between the waveguide is

a) 0

b) 1

c) -1

d) Infinite

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11. The distance between two terminated plates is given by the

a) Guided wavelength

b) 2(guided wavelength)

c) Guided wavelength/2

d) (Guided wavelength)/4

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12. Find the guided wavelength if the distance between the two conducting plates in the waveguide is 2 cm.

a) 4cm

b) 2cm

c) 1cm

d) 0.5cm

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## Set 5

1. The divergence theorem converts

a) Line to surface integral

b) Surface to volume integral

c) Volume to line integral

d) Surface to line integral

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

a) True

b) False

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

a) True

b) False

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4. Find the charged enclosed by a sphere of charge density ρ and radius a.

a) ρ (4πa^{2})

b) ρ(4πa^{3}/3)

c) ρ(2πa^{2})

d) ρ(2πa^{3}/3)

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^{2}sin θ dr dθ dφ and on integrating with r = 0->a, φ = 0->2π and θ = 0->π, we get Q = ρ(4πa

^{3}/3).

5. Evaluate Gauss law for D = 5r^{2}/4 i in spherical coordinates with r = 4m and θ = π/2 as volume integral.

a) 600

b) 588.9

c) 577.8

d) 599.7

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^{2}sin θ dr dθ dφ. On integrating, r = 0->4, φ = 0->2π and θ = 0->π/4, we get Q = 588.9.

6. Compute divergence theorem for D = 5r^{2}/4 i in spherical coordinates between r = 1 and r = 2 in volume integral.

a) 80 π

b) 5 π

c) 75 π

d) 85 π

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^{2}sin θ dr dθ dφ. On integrating, r = 1->2, φ = 0->2π and θ = 0->π, we get Q = 75 π.

7. Compute the Gauss law for D = 10ρ^{3}/4 i, in cylindrical coordinates with ρ = 4m, z = 0 and z = 5, hence find charge using volume integral.

a) 6100 π

b) 6200 π

c) 6300 π

d) 6400 π

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^{2}and dv = ρ dρ dφ dz. On integrating, ρ = 0->4, φ = 0->2π and z = 0->5, we get Q = 6400 π.

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

a) area of cube

b) area of cuboid

c) volume of cube

d) distance of vector

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9. Compute the charge enclosed by a cube of 2m each edge centered at the origin and with the edges parallel to the axes. Given D = 10y^{3}/3 j.

a) 20

b) 70/3

c) 80/3

d) 30

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^{2}∫∫∫Div (D) dv = ∫∫∫ 10y

^{2}dx dy dz. On integrating, x = -1->1, y = -1->1 and z = -1->1, we get Q = 80/3.

10. Find the value of divergence theorem for the field D = 2xy i + x^{2} j for the rectangular parallelepiped given by x = 0 and 1, y = 0 and 2, z = 0 and 3.

a) 10

b) 12

c) 14

d) 16