# Multiple choice question for engineering

## Set 1

1. Identify which of the following is not a transmission line?

a) Telephone lines

b) Power transmission

c) Underground cables

d) Cavity resonators

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2. The open wire transmission line consists of

a) Conductor

b) Dielectric

c) Both conductor and dielectric

d) Either conductor or dielectric

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3. Telephone lines and power lines are open wire transmission lines. State true/false.

a) True

b) False

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4. The cable transmission line consists of

a) Conductors

b) Insulators

c) Insulated conductors

d) Insulated conductors with dielectric

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5. The conductors lie perpendicularly with the dielectric in the cable line. State true/false.

a) True

b) False

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6. The coaxial cable consists of

a) Conductors

b) Dielectric

c) Conductor with dielectric

d) Two conductors with dielectric

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7. The coaxial cable are used in

a) Telephone cables transmission

b) Power transmission

c) Television signal transmission

d) Short wave transmission

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8. Identify which is not a type of waveguide.

a) Rectangular

b) Circular

c) Cylindrical

d) Cavity resonator

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9. The range of frequencies handled by the waveguides is in

a) Hz

b) KHz

c) MHz

d) GHz

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10. The range of frequencies operated by the coaxial cables is in

a) Hz

b) kHz

c) MHz

d) GHz

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11. The cut off frequency for waveguide operation is

a) 2 MHz

b) 6 GHz

c) 4 MHz

d) 6 MHz

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12. The highest means of communication is

a) Internet

b) Telephone

c) Television

d) Radio

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## Set 2

1. The phenomenon employed in the waveguide operation is

a) Reflection

b) Refraction

c) Total internal reflection

d) Adsorption

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2. The dominant mode in waveguide is the mode which has

a) Highest frequency

b) Highest wavelength

c) Lowest phase constant

d) Highest attenuation

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3. The modes are calculated from which parameter?

a) Frequency

b) Wavelength

c) Phase constant

d) V number

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^{2}/2.

4. The circular waveguides use which function in the frequency calculation?

a) Laplace function

b) Schottky function

c) Bessel function

d) Transfer function

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5. The scattering parameters are used to indicate the

a) Permittivity and permeability

b) Electric and magnetic field intensities

c) Reflection and transmission coefficients

d) Frequency and wavelength

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6. Which of the following two parameter models cannot be used to represent a transmission line?

a) H parameter model

b) T parameter model

c) ABCD parameter model

d) S parameter model

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7. For the matched line, the parameters S_{12} and S_{21} are

a) 1

b) 0

c) -1

d) ∞

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_{12}and S

_{21}are the reflection coefficients. For a matched line, the reflection coefficients are zero. Thus the parameters S

_{12}and S

_{21}are also zero.

8. The waveguides are materials with characteristics of

a) Low bulk resistivity

b) High bulk resistivity

c) High conductivity

d) Low conductivity

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9. The parameters S_{11} and S_{22} indicate the transmission coefficients. State true/false.

a) True

b) False

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_{11}and S

_{22}indicate the transmission coefficients and the parameters S

_{21}and S

_{12}indicate the reflection coefficients.

10. The waveguides increase the transmission of the electromagnetic waves. State true/false.

a) True

b) False

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## Set 3

1. The point form of Ampere law is given by

a) Curl(B) = I

b) Curl(D) = J

c) Curl(V) = I

d) Curl(H) = J

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2. The Ampere law is based on which theorem?

a) Green’s theorem

b) Gauss divergence theorem

c) Stoke’s theorem

d) Maxwell theorem

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3. Electric field will be maximum outside the conductor and magnetic field will be maximum inside the conductor. State True/False.

a) True

b) False

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4. Find the magnetic flux density of a finite length conductor of radius 12cm and current 3A in air( in 10^{-6} order)

a) 4

b) 5

c) 6

d) 7

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^{-7}.Thus B = 4π x 10

^{-7}x 3/2π x 0.12 = 5x 10

^{-6}units.

5. Calculate the magnetic field intensity due to a toroid of turns 50, current 2A and radius 159mm.

a) 50

b) 75

c) 100

d) 200

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6. Find the magnetic field intensity due to an infinite sheet of current 5A and charge density of 12j units in the positive y direction and the z component is above the sheet.

a) -6

b) 12k

c) 60

d) 6

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7. Find the magnetic field intensity due to an infinite sheet of current 5A and charge density of 12j units in the positive y direction and the z component is below the sheet.

a) 6

b) 0

c) -6

d) 60k

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8. Find the current density on the conductor surface when a magnetic field H = 3cos x i + zcos x j A/m, for z>0 and zero, otherwise is applied to a perfectly conducting surface in xy plane.

a) cos x i

b) –cos x i

c) cos x j

d) –cos x j

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9. When the rotational path of the magnetic field intensity is zero, then the current in the path will be

a) 1

b) 0

c) ∞

d) 0.5

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10. Find the magnetic field intensity when the current density is 0.5 units for an area up to 20 units.

a) 10

b) 5

c) 20

d) 40

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## Set 4

1. The intrinsic impedance of a wave with electric and magnetic field of 10 and 8 respectively is

a) 1.6

b) 1.11

c) 1.25

d) 0.8

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2. The intrinsic impedance is defined as the ratio of the magnetic field to the electric field of the electromagnetic wave. State true/false

a) True

b) False

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3. The intrinsic impedance in free space is

a) 60π

b) 12π

c) 6π

d) 120π

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4. The propagation constant is a complex quantity. State true/false.

a) True

b) False

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5. Calculate the propagation constant of a wave with impedance and admittance given by 32 and 12 respectively.

a) 19.6

b) 17.6

c) 15.6

d) 13.6

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6. The intrinsic angle is 25^{0}, find the loss angle.

a) 12.5

b) 50

c) 25

d) 75

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7. The standing wave ratio of the wave with maximum and minimum electric field intensities of 12 and 4 is

a) 12

b) 4

c) 3

d) 48

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_{MAX}/E

_{MIN}. Thus for the given data, S = 12/4 = 3.

8. The standing wave ratio of a wave travelling through two media having intrinsic impedances of 3 and 2 is

a) ^{2}⁄_{3}

b) ^{3}⁄_{2}

c) ^{1}⁄_{5}

d) 5

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9. The reflection coefficient of a wave travelling through two media having electric intrinsic impedances of 3 and 5 respectively is

a) 2

b) 8

c) ^{5}⁄_{3}

d) 1/4

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10. The reflection coefficient of a wave travelling through two media having magnetic intrinsic impedances of 2 and 1 respectively is

a) ^{1}⁄_{2}

b) ^{1}⁄_{3}

c) ^{1}⁄_{4}

d) ^{1}⁄_{5}

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11. The transmission coefficient of a wave travelling through two media having electric intrinsic impedances of 3 and 2 respectively is

a) ^{2}⁄_{2}

b) ^{8}⁄_{9}

c) ^{4}⁄_{5}

d) ^{1}⁄_{4}

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12. The transmission coefficient of a wave travelling through two media having electric intrinsic impedances of 3 and 4 respectively is

a) ^{2}⁄_{3}

b) ^{8}⁄_{9}

c) ^{2}⁄_{5}

d) ^{6}⁄_{7}

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^{3}⁄

_{4}+ 3 = 6/7.

## Set 5

1. Biot Savart law in magnetic field is analogous to which law in electric field?

a) Gauss law

b) Faraday law

c) Coulomb’s law

d) Ampere law

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^{2}, which is analogous to the electric field F = q1q2/4πεr

^{2}, which is the Coulomb’s law.

2. Which of the following cannot be computed using the Biot Savart law?

a) Magnetic field intensity

b) Magnetic flux density

c) Electric field intensity

d) Permeability

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3. Find the magnetic field of a finite current element with 2A current and height 1/2π is

a) 1

b) 2

c) 1/2

d) 1/4

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4. Calculate the magnetic field at a point on the centre of the circular conductor of radius 2m with current 8A.

a) 1

b) 2

c) 3

d) 4

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5. The current element of the solenoid of turns 100, length 2m and current 0.5A is given by,

a) 100 dx

b) 200 dx

c) 25 dx

d) 50 dx

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6. Find the magnetic field intensity at the centre O of a square of the sides equal to 5m and carrying 10A of current.

a) 1.2

b) 1

c) 1.6

d) 1.8

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7. Find the magnetic flux density when a point from a finite current length element of current 0.5A and radius 100nm.

a) 0

b) 0.5

c) 1

d) 2

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^{-7}, I = 0.5 and r = 10

^{-7}, we get B = 4π x 10

^{-7}x 0.5/2π x 10

^{-7}= 1 unit.

8. In a static magnetic field only magnetic dipoles exist. State True/False.

a) True

b) False

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9. The magnetic field intensity will be zero inside a conductor. State true/false.

a) True

b) False

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10. Find the magnetic field when a circular conductor of very high radius is subjected to a current of 12A and the point P is at the centre of the conductor.

a) 1

b) ∞

c) 0

d) -∞