Multiple Choice Questions in Electronics Engineering Part 3

Multiple Choice Questions in Electronics Engineering Part 3

1.      Which of the following is a natural magnet?

A. Steel

B. Magnesia

C. Lodestone

D. Soft iron

2.      Define as that pole which when placed in air from a similar and equal pole repels it with a force of newtons

A. North pole

B. South pole

C. Unit pole

D. Magnetic pole

3.      The point in a magnet where the intensity of magnetic lines of force is maximum

A. Magnetic pole

B. South pole

C. North pole

D. Unit pole

4.      The straight line passing through the two poles of magnet is called

A. Real axis

B. Cartesian axis

C. Magnetic axis

D. Imaginary axis

5.      The branch of Engineering which deals with the magnetic effect of electric current is known as

A. Magnetism

B. Electromagnetism

C. Electrical engineering

D. Electronics engineering

6.      The space outside the magnet where its pole have a force of attraction or repulsion on a magnetic pole is called

A. Magnetic field

B. Electric field

C. Electromagnetic field

D. Free Space Field

7.      The total number of magnetic lines of force in a magnetic field is called

A. Magnetic flux

B. Magnetic flux density

C. Magnetic flux intensity

D. Magnetic potential

8.      The phenomenon by which a magnetic substance becomes a magnet when it is place near a magnet

A. Magnetic effect

B. Magnetic phenomenon

C. Magnetic induction

D. Electromagnetic induction

9.      Which of the following magnetic materials can be easily magnetized in both direction?

A. Soft magnetic materials

B. Hard magnetic materials

C. High hysteresis loss materials

D. Low hysteresis loss materials

10.  Which of the following materials has permeability slightly less than that of free space?

A. Paramagnetic

B. Non- magnetic

C. Ferromagnetic

D. Diamagnetic

11.  Materials whose permeabilities are slightly greater than that of free space

A. Paramagnetic

B. Non- magnetic

C. Ferromagnetic

D. Diamagnetic

12.  Materials that have very high permeabilities (hundreds and even thousands times of that of free space)

A. Paramagnetic

B. Non- magnetic

C. Ferromagnetic

D. Diamagnetic

13.  The current of electric circuit is analogous to which quantity of a magnetic circuit

A. Mmf

B. Flux

C. Flux density

D. Reluctivity

14.  What is the diameter of an atom?

A. About 10^-10 m

B. About 10^-10 cm

C. About 10^-10 mm

D. About 10^-10 µm

15.  Defined as a closed path in which magnetic induction or flux flows

A. Electric circuit

B. Magnetic circuit

C. Electronic circuit

D. Electromagnetic circuit

16.  The force which set ups or tends to set up magnetic flux in a magnetic circuit

A. Dynamic force

B. Electromotive force

C. Potential difference

D. Magnetomotive force

17.  Referred to as the specific reluctance of a material

A. Resistivity

B. Reluctivity

C. Conductivity

D. Permeability

18.  The property of a material which opposes the creation of magnetic flux in it

A. Resistance

B. Reluctance

C. Permeance

D. Conductance            

19.  It is the reciprocal of reluctance and implies the case of readiness with which magnetic flux is developed.

A. Resistance

B. Conductance

C. Permeance

D. Inductance

20.  The ability of a material to conduct magnetic flux through it.

A. Permittivity

B. Reluctivity

C. Conductivity

D. Permeability

21.  The ratio of the permeability of material to the permiabiity of air or vacuum.

A. Relative permeability

B. Relative permittivity

C. Relative conductivity

D. Relative reluctivity

22.  Permeance is analogous to

A. Conductance

B. Reluctance

C. Admittance

D. Resistance

23.  The property of magnetic materials of retaining magnetism after withdrawal of the magnetizing force is known as

A. Retentivity

B. Reluctivity

C. Resistivity

D. Conductivity

24.  The quantity of magnetism retained by a magnetic material after withdrawal of the magnetizing force is called

A. Leftover magnetism

B. Hysteresis

C. Residual magnetism

D. Coercivity

25.  The amount of magnetizing force to counter balance the residual magnetism of a magnetic material is referred to as

A. Reluctivity

B. Susceptivity

C. Coercivity

D. Retentivity

26.  The ratio of the total flux (flux in iron path) to the useful flux (flux in air gap)

A. Leakage flux

B. Leakage current

C. Leakage coefficient

D. Leakage factor

27.  Defined as the number of lines per unit area through any substance in a plane at right angles to the lines of force

A. Flux

B. Flux lines

C. Flux density

D. Flux intensity

28.  Defined as the flux density produced in it due to its own induced magnetism

A. Magnetic field intensity

B. Electric field intensity

C. Electromagnetic field intensity

D. Intensity magnetization

29.  The force acting on a unit n- pole placed at that point is called

A. Magnetic field intensity

B. Electric field intensity

C. Electromagnetic field intensity

D. Intensity magnetization

30.  The ratio between the intensity of magnetization produced in a substance to the magnetizing force producing it

A. Magnetic Reluctivity

B. Magnetic Resistivity

C. Magnetic susceptibility

D. Magnetic conductivity

Multiple Choice Questions in Electronics Engineering Part 2

Multiple Choice Questions in Electronics Engineering Part 2

1.      One farad equals

A. 1 coulomb/volt

B. 1 newton/coulomb

C. 1 newton-meter

D. 1 volt/second/ampere

2.      Which of the following is used by permanent magnets as the magnetic material?

A. iron

B. nickel

C. soft steel

D. hardened steel

3.      Which of the following is used by temporary magnets as the magnetic material?

A. Hardened steel

B. Cobalt steel

C. Soft iron

D. Tungsten steel

4.      What is the main advantage of temporary magnets?

A. The magnetic flux can be changed.

B. Hysteresis can be decreased.

C. Magnetic materials can be used.

D. Abundance of ferromagnetic material that can be temporarily magnetized.

5.      Permanent magnets can be found in

A. electric bells

B. earphones

C. relays

D. dynamic loudspeakers

6.      Temporary magnets are commonly employed in

A. electric instruments

B. motors

C. moving coils loudspeakers

D. magnetos

7.      The force between two magnetic poles is _______ their pole strengths.

A. directly proportional to

B. the sum of

C. inversely proportional to

D. the product of

8.      If the distance between two magnetic poles decreases by 2 times, the force between them

A. decreases two times

B. increases four times

C. increases two times

D. decreases four times

9.      The force between two magnetic poles is _____ the relative permeability of the medium.

A. directly proportional to

B. independent of

C. inversely proportional to

D. equal to

10.  Two similar poles, each 1Wb, placed 1 m apart in air will experience a repulsive force of

A. 63000 N

B. 63 × 10^-3 N

C. 8 × 10^12 N

D. 796 kN

11.  One weber of flux is equal to _______ magnetic lines of force.

A. 10^6

B. 10^10

C. 4π × 10^7

D. 10^8

12.  The unit of flux density is

A. Wb/m

B. Tesla

C. At/m

D. N/Wb

13.  What is the typical saturation flux density for most magnetic materials?

A. 4 Wb/m^2

B. 5 Wb/m^2

C. 1 Wb/m^2

D. 2 Wb/m^2

14.  Magnetic field intensity is a ________ quantity.

A. scalar

B. phasor

C. vector

D. variable

15.  The force acting on a pole of 5 Wb is 25 N. What is the intensity of the magnetic field?

A. 5 N/Wb

B. 25 N/Wb

C. 125 N/Wb

D. 0.2 N/Wb

16.  The relative permeability of a magnetic material is 10^5. What is its permeability?

A. 4π × 10^5 H/m

B. 4π × 10^-12 H/m

C. 4π × 10^-2 H/m

D. 4π × 10^-7 H/m

17.  Which of the following has the highest permeability?

A. Soft iron

B. Steel

C. Air

D. Permalloy

18.  A magnetic pole produces 5000 field lines. How much is the flux in webers?

A. 50 × 10^-6

B. 5 × 10^-6

C. 500 × 10^-6

D. 500 × 10^-5

19.  As the magnetic intensity decreases, the relative permeability of a magnetic material

A. decreases

B. remains the same

C. increases

D. becomes zero

20.  The permeability of a material having a flux density of 5 Wb/m^2 is 10^-5 H/m. What is the value of magnetizing force?

A. 5 × 10^-5 N/Wb

B. 500 × 10^3 N/Wb

C. 4π × 10^-7 N/Wb

D. 4π × 10^7 N/Wb

21.  When the relative permeability of a material is slightly less than 1, it is called _____ material.

A. diamagnetic

B. ferromagnetic

C. paramagnetic

D. non-magnetic           

22.  When the relative permeability of a material is slightly more than 1, it is called ______ material.

A. diamagnetic

B. ferromagnetic

C. paramagnetic

D. non-magnetic

23.  Which of the following is a diamagnetic material?

A. Aluminum

B. Silver

C. Air

D. Cobalt

24.  Which of the following is a paramagnetic material?

A. Carbon

B. Bismuth

C. Copper

D. Oxygen

25.  The greater percentage of materials is _________.

A. diamagnetic

B. paramagnetic

C. ferromagnetic

D. non-magnetic

26.  When the relative permeability of a material is much greater than 1, it is called _______ material.

A. diamagnetic

B. ferromagnetic

C. paramagnetic

D. non-magnetic

27.  The flux density in an air-cored coil is 10^-3 Wb/m^2. With a cast iron core of relative permeability 100 inserted, the flux density will become

A. 10^-3 Wb/m^2

B. 10^-2 Wb/m^2

C. 10^3 Wb/m^2

D. 0.1 Wb/m^2

28.  At/m is a unit of

A. mmf

B. magnetic force

C. reluctance

D. magnetic flux density

29.  The direction of force o a current carrying conductor placed in a magnetic field can be found by

A. Cork screw rule

B. Fleming’s left hand rule

C. Fleming’s right hand rule

D. using a compass

30.  When a current carrying conductor is placed in a magnetic field, the maximum force will act on the conductor when the conductor is at an angle of _______ to the magnetic field.

A. 45^o

B. 60^o

C. 30^o

D. 90^o