Electricity Fundamentals MCQ Solved Paper for CEED

1. A law that states that the current in a thermionic diode varies directly with the three- halves power of anode voltage and inversely with the square of the distance between the electrodesa provided operating conditions are such that the current is limited only by the space charge.
A. Hall's law
B. Joule's law
C. Child's law
D. Coulomb's law
Answer : C

2. The magnetic flux through a coil changes. This results to the induced emf acting in a direction as to
A. Oppose the change
B. Aid the change
C. Either oppose or aid the change
D. Neither oppose nor aid the change
Answer : A

3. An alloy of 40 percent iron and 60 percent nickel.
A. Alnico
B. Permalloy
C. Hipernik
D. Manganin
Answer : C

4. An electron- volt (eV) is a unit of
A. Energy
B. Potential difference
C. Charge
D. Momentum
Answer : A

5. Who discovered that a current-carrying conductor would move when placed in a magnetic field?
A. Michael Faraday
B. Andre Ampere
C. Hans Christian Oersted
D. Gustav Robert Kirchhoff
Answer : A

6. Flux density is measured in
A. Tesia
B. Weber
C. Ampere- turn
D. Maxwell
Answer : A

7. The property of a material which opposes the creation of magnetic flux in it
A. Resistance
B. Reluctance
C. Permeance
D. Conductance
Answer : B

8. 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
Answer : C

9. Which of the following is used by permanent magnets as the magnetic material?
A. iron
B. nickel
C. soft steel
D. hardened steel
Answer : D

10. Core materials of a good relay have _________ hysteresis loop.
A. large
B. narrow
C. very large
D. very narrow
Answer : B

11. The tiniest element of matter
A. Atom
B. Proton
C. Electron
D. Neutron
Answer : A

12. The flux density in an air-cored coil is 10^-3 Wb/m^2. With a cast iron core of relative permeability 100 inserteda 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
Answer : D

13. Back emf refers to the
A. Current equal to the applied emf
B. Opposing emf
C. Current opposing the applied emf
D. Voltage opposing the applied emf
Answer : D

14. The magnetic potential in a magnetic circuit can be measured in terms of
A. Mmf
B. Emf
C. Farad
D. Coulomb
Answer : A

15. Calculate the flux density that will be produced by the field intensity of 2000 a. t/m for a permeability of 126 x 10^-6 T/A.t/m
A. 0.252 G
B. 0.252 x 10^-2 T
C. 0.252 T
D. 0.252 x 10^-2 G
Answer : C

16. __________ is a substance of whose molecules consist of the same kind of atom.
A. Mixture
B. Compound
C. Element
D. Isotope
Answer : C

17. The permittivity of a material is given by one of the following formulas.
A. DE
B. E/D
C. D^2/E
D. D/E
Answer : D

18. Electric lines of force leave or enter the charge surface at an angle of
A. 30o
B. 45 o
C. 90o
D. depending upon the angle of launch and entry
Answer : C

19. All magnetic field originates from
A. moving electric charge
B. Iron atoms
C. Magnetic domain
D. Permanent magnets
Answer : A

20. The evaporation of electrons from a heated surface is called
A. Radiation
B. Convection
C. Thermionic emission
D. Conduction
Answer : C

21. The magnetic field around the conductor is determined by the
A. Size of the conductor
B. Amount of current
C. Current divided by the resistance
D. Resistance divided by the current
Answer : B

22. The emission of electrons from hot bodies is called
A. Radiation effect
B. Edison effect
C. Skin effect
D. Half effect
Answer : B

23. Electron is a Greek word for
A. amber
B. Fire
C. Stone
D. Heat
Answer : A

24. One weber of flux is equal to _______ magnetic lines of force.
A. 10^6
B. 10^10
C. 4 × 10^7
D. 10^8
Answer : D

25. What bond is formed when one or more electrons in the outermost energy orbit of an atom are transferred to another?
A. Ionic
B. Covalent
C. Metallic
D. Van der Waals
Answer : A

26. What is the value of the absolute permittivity of air?
A. 8.854 F/m
B. 8.854 × 10^-12 mF/m
C. 8.854× 10^-12 F/m
D. 8.854 × 10^-12 F/m
Answer : C

27. Magnetic field intensity is a ________ quantity.
A. scalar
B. phasor
C. vector
D. variable
Answer : C

28. The quantity 10^6 maxwells is equivalent to one
A. Weber
B. Gauss
C. Gilbert
D. Tesla
Answer : A

29. What is the usual value of leakage coefficient for electrical machines?
A. 0.5 to 1
B. 1 to 5
C. 5 to 10
D. 1.15 to 1.25
Answer : D

30. States that the ratio of the thermal conductivity is proportional to the absolute temperature for all metals.
A. Wien's displacement law
B. Hartleys law
C. Hall's law
D. Wiedemann Franz law
Answer : D

31. 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.
Answer : A

32. 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
Answer : C

33. Materials whose permeabilities are slightly greater than that of free space
A. Paramagnetic
B. Non- magnetic
C. Ferromagnetic
D. Diamagnetic
Answer : A

34. 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
Answer : A

35. There are how many compounds available in nature?
A.
B.
C. 300a000
D. Unlimited
Answer : D

36. 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. 4 × 10^7N/Wb
D. 4 × 10^7N/Wb
Answer : B

37. A magnetic circuit carries a flux iin the iron part and a fluxgin the air gap. What is the leakage coefficient?
A. i/g
B. i × g
C. g/ i
D. i + g
Answer : A

38. The reluctance of a magnetic circuit is not dependent on which of the following?
A. Number of turns of coil
B. Magnetomotive force
C. Flux density in the circuit
D. Current in the coil
Answer : C

39. 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 �m
Answer : A

40. The temperature coefficient of resistance of conductors is
A. positive
B. zero
C. negative
D. infinite
Answer : A

41. What is the SI unit of conductivity?
A. Ohms/m
B. Ohms-m
C. Siemens-m
D. Siemens/m
Answer : D

42. A one cubic cm of copper has how many free electrons at room temperature?
A. 80 × 10^18
B. 8.5 × 10^22
C. 20 × 10^10
D. 50 × 10^20
Answer : B

43. The physical motion resulting from the forces of magnetic fields is called
A. Motor action
B. Rotation
C. Repulsion
D. Torque action
Answer : A

44. What is used as the dielectric material in high voltage transformers?
A. Mica
B. Paraffin
C. Porcelain
D. Oiled paper
Answer : C

45. A group of magnetically aligned atoms is called
A. Range
B. Lattice
C. Domain
D. Crystal
Answer : C

46. The B-H curve for ________ is a straight line passing through the origin.
A. cobalt
B. air
C. hardened steel
D. soft iron
Answer : B

47. The mass of proton is __________ the mass of an electron.
A. equal to
B. about 1837 times
C. less than
D. 200 tim es
Answer : B

48. 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
Answer : A

49. Hysteresis refers to the ______ between flux density of the material and the magnetizing force applied.
A. Leading effect
B. Ratio
C. Equality
D. Lagging effect
Answer : D

50. If the value of 25 a conductor is 1/255 per oCa then the value of 20is
A. 1/300 per oC
B. 1/250 peroC
C. 1/230 per oC
D. 1/260 per oC
Answer : B