1000+ Electricity Fundamentals MCQ for RRB JE [Solved]

1. Which of the following materials has the highest dielectric strength?
A. Glass
B. Oiled paper
C. Mica
D. Air
Answer : A

2. Which of the following statements is TRUE?
A. Silicon dioxide is a good
B. The current carriers in conductors are valence electrons
C. For conductorsa the valence electron are strongly attracted to the nucleus
D. The valence electrons are located in the nucleus of an atom
Answer : B

3. How much is the flux in Weber in the above problem?
A. 2 x 10^-5
B. 2 x 10^-3
C. 2 x 10^5
D. 2 x 10^3
Answer : A

4. What is the cgs unit of magnetomotive force?
A. Gilbert
B. Ampere- turn
C. Maxwell
D. Weber
Answer : A

5. 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

6. 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
Answer : A

7. 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

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

9. A magnetic flux of 2.5 x10^4 Wb through an area of 5 x10^4 square meters results in
A. 5 Wb
B. 0.5 Tesia of flux density
C. 5x 10^-5 Wb of flux
D. 5000 Tesia of flux density
Answer : B

10. The magnetic field of a bar magnet most closely resembles the magnetic field of
A. a horseshoe magnet
B. a straight current- carrying wire
C. a stream of electrons moving parallel to one another
D. a current- carrying wire loop
Answer : D

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

12. The resistance of a material is ____________ its area of cross-section.
A. directly proportional
B. independent of
C. inversely proportional to
D. equal to
Answer : C

13. Which of the following is a paramagnetic material?
A. Carbon
B. Bismuth
C. Copper
D. Oxygen
Answer : D

14. Which of the following has the highest permeability?
A. Soft iron
B. Steel
C. Air
D. Permalloy
Answer : D

15. 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
Answer : A

16. 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

17. The unit of flux density is
A. Wb/m
B. Tesla
C. At/m
D. N/Wb
Answer : B

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

19. How many electrons are needed in the valence orbit to give a material's stability?
A.
B.
C.
D.
Answer : A

20. Amorphous solid is also called
A. Crystalline
B. Non- crystalline
C. Polycrystalline
D. Homogenous
Answer : B

21. 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

22. Which of the following is a paramagnetic material?
A. Carbon
B. Copper
C. Bismuth
D. Oxygen
Answer : D

23. 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

24. What is the SI unit of specific resistance or resistivity?
A. Ohm-circular mil per inch
B. Ohm-circular mil per foot
C. Ohm-m
D. Ohm-cm
Answer : C

25. Lenz' law states that the direction of the induced emf and hence current
A. Is determined by the rate of current flux
B. Is found by the right hand rule
C. Is found by the left hand rule
D. Always opposes the cause producing it
Answer : D

26. 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

27. 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

28. 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

29. A commercial alloy of aluminum nickela and iron with cobalta copper and titanium added to produce about 12 grades.
A. Alnico
B. Brass
C. Aluminum
D. Constantan
Answer : A

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

31. The K shell or the first shell has how many permissible number of orbiting electrons?
A.
B.
C.
D.
Answer : B

32. Electric field intensity is a ________.
A. scalar
B. phasor
C. vector
D. variable
Answer : C

33. Temporary magnets are commonly employed in
A. electric instruments
B. motors
C. moving coils loudspeakers
D. magnetos
Answer : B

34. A negative ion results when an atom gains an additional
A. Electron
B. Proton
C. Neutron
D. Atom
Answer : A

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

36. Refers to the non- metallic materials that have the ferromagnetic properties of iron.
A. Ferrites
B. Ferromagnetic
C. Diamagnetic
D. Paramagnetic
Answer : A

37. Ohm's law cannot be applied to which material?
A. Copper
B. Silver
C. Silicon carbide
D. Aluminum
Answer : C

38. 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

39. Who demonstrated that there are magnetic effects around every current-carrying conductor and that current-carrying conductors can attract and repel each other just like magnets?
A. Luigi Galvani
B. Hans Christian Oersted
C. Charles Coulomb
D. Andre Ampere
Answer : D

40. Mmf in a magnetic circuit corresponds to _____ in an electric circuit
A. Emf
B. Voltage drop
C. Electric Field Intensity
D. Potential gradient
Answer : A

41. 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

42. 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

43. 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

44. 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

45. The core of a magnetic equipment uses a magnetic material with
A. Least permeability
B. Low permeability
C. Moderate permeability
D. High permeability
Answer : D

46. 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

47. The electrons in the last orbit of an atom are called _______ electrons.
A. free
B. valence
C. bound
D. thermionic
Answer : B

48. One electron volt (1 eV) is equivalent to _____ joules
A. 1.3 x 10^-19
B. 1.4 x 10^-19
C. 1.5 x 10^-19
D. 1.6 x 10^-19
Answer : D

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

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