GRE - Electricity Fundamentals 1000+ MCQ [Solved] PDF Download

1. 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

2. Which of the following is a diamagnetic material?
A. Aluminum
B. Silver
C. Air
D. Cobalt
Answer : C

3. The B-H curve of ________ is not a straight line.
A. air
B. wood
C. silicon steel
D. soft iron
Answer : D

4. If the number of valence electrons of an atom is less than 4a the substance is called
A. a conductor
B. a semiconductor
C. an insulator
D. a superconductor
Answer : A

5. 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

6. If the right handed bottle-opener cork screw is assumed to be along the conductor so as to advance in the direction of current flow, the motion of its handle will indicate the direction of magnetic flux produced around the conductor. This is known as
A. Right hand rule
B. Left hand rule
C. Cork screw rule
D. End rule
Answer : C

7. The electric potential across part AB of a circuit is 5 V; point A being at higher potential. If a charge of 5 Cmoves from A to Ba then energy released as
A. 5 joules
B. 25 joules
C. 10 joules
D. 100 joules
Answer : B

8. The emf produced in a wire by its motion across a magnetic field does not depend upon the
A. Diameter of the wire
B. Length of the wire
C. Orientation of the wire
D. Flux density of the field
Answer : A

9. The amount of magnetizing force to counter balance the resid magnetic material is referred to as
A. Reluctivity
B. Susceptivity
C. Coercivity
D. Retentivity
Answer : C

10. Electric field intensity is measured in
A. volts/meter
B. Newton/meter
C. Newton-meter
D. Amperes/meter
Answer : A

11. 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

12. Whenever a conductor cuts magnetic fluxa an emf is induced in it. This is known as
A. Coulomb's law
B. Joule's law
C. Faraday's law
D. Ohm's law
Answer : C

13. 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

14. When a conductor is stationary and the magnetic field is moving or changing the emf induced is called
A. Statically induced emf
B. Mutually induced emf
C. Self induced emf
D. Dynamically induced emf
Answer : A

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

16. The force between two magnetic poles varies with the distance between them. The variation is ______ to the square of that distance.
A. Equal
B. Greater than
C. Directly proportional
D. Inversely proportional
Answer : D

17. The air space between poles of magnets
A. Air gap
B. Free space
C. Vacuum
D. Atmosphere
Answer : A

18. 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
Answer : D

19. A germanium atom has an atomic weight of72. How many neutrons are there?
A.
B.
C.
D.
Answer : B

20. Steel is hard to magnetize because of its
A. Low permeability
B. High permeability
C. High density
D. High retentivity
Answer : A

21. The relative permeability of a magnetic material is 10^5. What is its permeability?
A. 4 × 10^5 H/m
B. 4 × 10^-12 H/m
C. 4× 10^-2 H/m
D. 4 × 10^7H/m
Answer : C

22. Three charges of +5 Ca -6 C and +9 C are placed inside a sphere. What is the total flux passing through the surface of sphere?
A. 8 C
B. 14 C
C. 20 C
D. -6 C
Answer : A

23. What bond is formed when electrons in the outermost energy orbits of the atoms are shared between two or more electrons?
A. Ionic
B. Covalent
C. Metallic
D. Van der Waals
Answer : B

24. Calculate the permeability (in T/A. t/m) of a magnetic material that has a relative permeability of 300
A. 3.78 x 10^4
B. 3.78 x 10^-5
C. 3.78 x 10^-3
D. 3.78 x 10^-6
Answer : A

25. If the length and area of cross-section of a wire are doubleda then its resistance
A. becomes four times
B. becomes sixteen times
C. remains the same
D. becomes two times
Answer : C

26. A substance that attracts pieces iron
A. Conductor
B. Semiconductor
C. Magnet
D. All of the above
Answer : C

27. A factor used to correct for the electrostatic forces of the more distant ions in an ionic solid.
A. Avogadro's number
B. Planck's constant
C. Boltzmann's constant
D. Madelung constant
Answer : D

28. Small voltages generated by a conductor with current in an external magnetic field.
A. Skin effect
B. Magnetic effect
C. Hall effect
D. Flywheel Effect
Answer : C

29. Hipernik is an alloy containing __________ iron and __________ nickel.
A. 40% ; 60%
B. 60% ; 40%
C. 50% ; 50%
D. 70% ; 30%
Answer : A

30. The lagging effect between flux density of the material and the magne
A. Permeance
B. Eddy current
C. Hysteresis
D. R eluctance
Answer : C

31. One ampere- turn is equivalent to _____ gilberts
A.
B.
C.
D.
Answer : B

32. One oersted (Oe) is equivalent to _____ Gb/cm.
A.
B.
C.
D.
Answer : A

33. Permanent magnets can be found in
A. electric bells
B. earphones
C. relays
D. dy namic loudspeakers
Answer : B

34. The magnitude of the induced emf in a coil is directly proportional to the rate of change of flux linkages. This is known as
A. Joule's Law
B. Faraday's second law of electromagnetic induction
C. Faraday's first law of electromagnetic induction
D. Coulomb's Law
Answer : B

35. If the relative permittivity of a material is 10a then its permittivity is
A. 4 × 10^7F/m
B. 4 × 10^-6 F/m
C. 8.854× 10^-11 F/m
D. 8.854 × 10^-12 F/m
Answer : C

36. The temperature coefficient of resistance of a conductor ______ with an increase in temperature.
A. increases
B. decreases
C. remains the same
D. becomes negative
Answer : B

37. This paper does not exhibit electricity because it contains the same number of
A. protons and electrons
B. neutrons and electrons
C. neutrons and positrons
D. atoms
Answer : A

38. If the value of 0 a conductor is 1/234 per oCa then the value of 18is
A. 1/218 per oC
B. 1/252 peroC
C. 1/272 per oC
D. 1/273 per oC
Answer : B

39. If the number of valence electrons of an atom is more than 4a the substance is called
A. a semiconductor
B. a conductor
C. an insulator
D. a semi-insulator
Answer : C

40. Refers to the magnetic lines
A. Flux
B. Hysteresis
C. Current
D. Magnetomotive force
Answer : A

41. 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

42. Cobalt is an example of a ______ material.
A. Paramagnetic
B. Diamagnetic
C. Ferromagnetic
D. Non- magnetic
Answer : C

43. 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
Answer : D

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

45. Who discovered the most important electrical effects which is the magnetic effect?
A. Hans Christian Oersted
B. Sir Charles Wheatstone
C. Georg Ohm
D. James Clerk Maxwell
Answer : A

46. Defined as a closed path in which magnetic induction or flux flows
A. Electric circuit
B. Magnetic circuit
C. Electronic circuit
D. Electromagnetic circuit
Answer : B

47. Flux linkages equals
A. Flux times area of core
B. Flux times number of turns times area of core
C. Flux times number of turns times length of core
D. Flux times number of turns
Answer : D

48. The magnetic flux through a wire loop in a magnetic field does not d
A. T he area of the loop
B. The magnitude of the field
C. The shape of the loop
D. The angle between the plane of the loop and the direction
Answer : C

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

50. What is the SI unit of conductance?
A. Siemens
B. Mhos
C. Ohms
D. 1/Ohms
Answer : A