Electricity Fundamentals MCQ Solved Paper for UPSC CDS

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

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

3. 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

4. One farad equals
A. 1 coulomb/volt
B. 1 newton/coulomb
C. 1 newton-meter
D. 1 volt/second/ampere
Answer : A

5. 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

6. Magnetic fields do not interact with
A. Moving permanent magnets
B. Stationary permanent magnets
C. Moving electric charges
D. Stationary electric charges
Answer : D

7. If the number of valence electrons of an atom is less than 4a then the substance is probably
A. a metal
B. an insulator
C. a non-metal
D. a semiconductor
Answer : A

8. The net electrical charge in an isolated system remains constant. This is known as
A. Law of conservation of charge
B. Coulomb's first law
C. Coulomb's second law
D. Law of conservation of energy
Answer : A

9. The temperature coefficient of resistance of eureka is
A. p ositive
B. negative
C. almost zero
D. i nfinite
Answer : C

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. 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

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

13. The reluctance of a magnetic circuit varies with
A. length × area
B. area � length
C. length � area
D. length + area
Answer : C

14. 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

15. Hysteresis loss can be reduced by one of the following.
A. Increasing mmf of the circuit
B. Using material narrow hysteresis loop
C. Using ferromagnetic core
D. Laminating the magnetic circuit
Answer : B

16. Under ordinary conditionsa a body is considered
A. positively charged
B. neutral
C. negatively charged
D. stable
Answer : B

17. The dielectric constant of most materials lies between
A. 1 and 10
B. 10 and 20
C. 20 and 50
D. 50 and 100
Answer : A

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

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

20. The phenomenon by which a subtracts pieces of iron
A. Magnetism
B. Electromagnetism
C. Naturalism
D. Materialism
Answer : A

21. The magnetic field inside a solenoid
A. is zero
B. is uniform
C. increases with distance from the axis
D. decreases with distance from the axis
Answer : B

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

23. A 6- V battery is connected across a solenoid of 100 turns having a resistance of 2 ?a Calculate the number of ampere turns?
A.
B.
C.
D.
Answer : C

24. Electric field intensity at a point due to a given charge ______ if the relative permittivity of the medium decreases.
A. decreases
B. remains unchanged
C. increases
D. b ecomes zero
Answer : C

25. The emf induced in a coil due to the change of its own flux linked with it is called
A. Mutually induced emf
B. Dynamically induced emf
C. Statically induced emf
D. Self induced emf
Answer : D

26. The electric field intensity between the parallel plate air capacitor is 20 N/C. If an insulating slab of relative permittivity 5 is placed between the platesa then electric field intensity will be
A. 20 N/C
B. 100 N/C
C. 4N/C
D. 40 N/C
Answer : C

27. 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

28. 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

29. When a wire loop is rotated in a magnetic field the direction of the induced emf changes one in every _______ revolution
A.
B.
C.
D.
Answer : B

30. Permeance of a magnetic circuit is _________ the cross-sectional area of the circuit.
A. directly proportional to
B. inversely proportional to
C. dependent of
D. independent of
Answer : A

31. 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

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

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

34. When the relative permeability of a material is slightly less than 1a it is called _____ material.
A. diamagnetic
B. ferromagnetic
C. paramagnetic
D. non-magnetic
Answer : A

35. 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

36. Electronic current in a wire is the flow of ____________ electrons.
A. free
B. valence
C. bound
D. loose
Answer : A

37. Why is it that the magnitude of magnetomotive force required for air gap is much greater than that required for iron part of a magnetic circuit?
A. Because air is a gas
B. Because air has the highest relative permeability
C. Because air is a conductor of magnetic flux
D. Because air has the lowest relative permeability
Answer : D

38. The uncharged particles which have no effect on its atomic charge.
A. Nucleons
B. Electrons
C. Protons
D. Neutrons
Answer : D

39. The ability of a mechanically stressed ferromagnetic wire to recognize rapid switching of magnetization when subjected to a dc magnetic field.
A. Wartheim effect
B. Wiedemann effect
C. Wiegand effect
D. Edison effect
Answer : C

40. What is the relative permittivity of air?
A.
B.
C. 8.854 × 10^-12
D. 4 × 10^7
Answer : B

41. Electromotive force in a circuit
A. causes free electrons to flow
B. increases the circuit resistance
C. maintains circuit resistance
D. is needed to make the circuit complete
Answer : A

42. If two similar charges 1 coulomb each are placed 1 m apart in aira then the force of repulsion is
A. 8 × 10^6 N
B. 9 × 10 ^9 N
C. 10^6 N
D. 5 × 10^6 N
Answer : B

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

44. 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

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

46. Magnetic effects of the earth as a huge magnet with north and south poles.
A. Diamagnetic
B. Ferromagnetic
C. Terrestrial magnetism
D. Terrestrial ferromagnetism
Answer : C

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

48. A test charge means a charge of
A. -1 C
B. 1 electron
C. +1 C
D. -20 C
Answer : C

49. 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

50. The unit of flux is _____ in cgs system.
A. Tesia
B. Gilbert
C. Maxwell
D. Oersted
Answer : C