BASIC ELECTRICAL PART -1
1) Filters are used to converta. Pulsating dc signal into a pure dc signal
b. Pure dc signal into a pulsating dc signal
c. Pulsating dc signal into a pure ac signal
d. Pulsating ac signal into a pure dc signal
ANSWER: Pulsating dc signal into a
pure dc signal
2) In DOL fuses are provided to protect against
a. Short circuit protection
b. Over voltage
c. Over current
d. Over load
ANSWER: Short circuit
protection
3) Kirchhoff's second law is based on law of conservation of
(A) charge
(B) energy
(C) momentum
(D) mass.
Answer: B
4. For carbon resistors what is the color for 5?
(A) Green
(B) Black
(C) Orange
(D) Gray.
Answer A
5. Which of the following can have positive or negative charge?
(A) Electron
(B) iron
(C) Hole
(D) Neutron.
Answer B
6. In a nickel-cadmium-alkali cell the electrolyte is
(A) sulphur acid
(B) potassium hydroxide
(C) zinc chloride
(D) ammonium chloride.
Answer B
7.Which method can be used for absolute measurement of resistances ?
(A)Ohm's law method
(B)Wheatstone bridge method
(C)Releigh method
(D) Lortentz method.
Answer B
8. How many different combinations may be obtained with three
resistors, each having the resistance R ?
(A) 3
(B) 4
(C) 5
(D) 6.
Answer B
9. A drawn wire of resistance 25 ohm is further drawn so that its
diameter becomes one fifth. Its resistance will now be
(A) 625 ohm
(B) 125 ohm
(C) 25 ohm
(D) 1 ohm.
Answer A
10. Certain substances lose their electrical resistance completely at finite
low temperatures. Such substances are called
(A) dielectrics
(B) super-conductors
(C) semi conductors
(D) perfect conductors.
Answer B
11. Temperature coefficient of resistance is expressed in terms of
(A) ohms / ohms oC
(B) mhos / ohm oC
(C) mhos / oC
(D) ohms / oC.
Answer A
12.Which of the following material is not used as fuse material?
(A) Silver
(B) Copper
(C) Aluminium
(D) Carbon.
Answer D
13. Two 1 kilo ohm, 1/2 W resistors are connected in series. Their
combined resistance value and wattage will be
(A) 2 kohm, 1 / 2 W
(B) 2 kohm, 1 W
(C) 2kohm, 2 W
(D) 1 kohm, 1 / 2 W.
Answer B
14. Three resistance of 6 ohm each are connected as shown in Figure
given below. The equivalent resistance between X1 and X2 is
(A) 2 ohm
(B) 4 ohm
(C) 8 ohm
(D) 12 ohm.
Answer A
15. Ohm's law is not applicable in all the following cases except
(A) Electrolysis
(B) Arc lamps
(C) Insulators
(D) Vacuum radio valves.
Answer C
16. In the color code white color represents the number
(A) 9
(B) 8
(C) 6
(D) 5.
Answer A
17. Which resistor will be physically larger in size ?
(A)10 ohm, 50 W
(B) 100 ohm, 10 W
(C) 1 kohm, 1 W
(D) 10 Mohm, 1/ 2 W.
Answer A
18. When current flows through heater coil it glows but supply wiring
does not glow because
(A) supply wiring is covered with insulation layer
(B) current through supply line flows at slower speed.
(C) supply wires arc made of superior material
(D) resistance of heater coil is more than that supply wires.
Answer D
19. Which among the below specified assertions are precisely related to
the conditions applicable for a path to be an improper sub graph?
A. Incidence of a single branch at a terminating node
B. Incidence of two branches at the remaining nodes
a. A is true & B is false
b. A is false & B is true
c. Both A & B are true
d. Both A & B are false
ANSWER: (c)
20. The condition for the validity under Ohm's law is
(A) Temperature at positive end should be more than the temperature at negative
end
(B) Current should be proportional to the size of resistance
(C) Resistance must be wire wound type
(D) Resistance must be uniform.
Answer D
21. A rheostat differs from potentiometer in the respect that
(A) rheostat has large number of turns
(B) rheostat offers larger number of tappings
(C) rheostat has lower wattage rating
(D) rheostat has higher wattage ratings.
Answer D
22 .Three elements having conductance G1, G2 and G3 are connected in
parallel. Their combined conductance will be
(A) 1/( 1/G1 + 1/G2 + 1/G3)
(B) (G1G2 + G2G3 + G3G1)/(G1 + G2 + G3)
(C) 1/(G1 + G2+ G3)
(D) G1 + G2 +G3
Answer D
23. A standard 60 W bulb is in series with a room heater and connected
across the mains. If the 60 W bulb is replaced by 100 W bulb
(A) the heater output will increase
(B) the heater output will reduce
(C) the heater output will remains unaltered.
Answer A
24. Variable resistors are
(A)Wire wound resistors
(B)Thin film resistors
(C)Thick film resistors
(D)All of the above.
Answer A
25. When checked with an ohm meter an open resistor reads
(A) zero
(B) high but within tolerance
(C) low but not zero
(D) infinite.
Answer D
26. Twelve wires of same length and same cross-section are connected in
the form of a cube as shown in figure below. If the resistance of each wire
is R, then the effective resistance between P and Q will be
(A)R
(B) 5 / 6 R
(C) 3 / 4 R
(D) 4 / 3 R.
Answer B
26. Twelve wires of same length and same cross-section are connected in
the form of a cube as shown in figure below. If the resistance of each wire
is R, then the effective resistance between P and Q will be
(A)R
(B) 5 / 6 R
(C) 3 / 4 R
(D) 4 / 3 R.
Answer B
27. Resistance across A and B in the circuit shown below is
(A) R
(B) 3 R
(C) 4 R
(D) 5 R.
Answer A
28. Lithium cells operates ranging from
a. -25 ° C to 25 ° C
b. -50 ° C to 25 ° C
c. -50 ° C to 75 ° C
d. -75 ° C to 75 ° C
ANS- C
29. Basic source of magnetism ______________.
(a) Charged particles alone
(b) Movement of charged particles
(c) Magnetic dipoles
(d) Magnetic domains
Ans B
30. Units for magnetic flux density
(a) Wb / m2
(b) Wb / A.m
(c) A / m
(d) Tesla / m
ANS A
31. Magnetic permeability has units as
(a) Wb / m2
(b) Wb / A.m
(c) A / m
(d) Tesla / m
Ans B
32. Magnetic permeability has units as
(a) Tesla
(b) Henry
(c) Tesla / m
(d) Henry / m
Ans D
33. Magnetic field strength’s units are
(a) Wb / m2
(b) Wb / A.m
(c) A / m
(d) Tesla / m
Ans c
34. Example for dia-magnetic materials
(a) super conductors
(b) alkali metals
(c) transition metals
(d) Ferrites
Ans A
35. Example for para-magnetic materials
(a) super conductors
(b) alkali metals
(c) transition metals
(d) Ferrites
Ans B
36. Example for ferro-magnetic materials
(a) super conductors
(b) alkali metals
(c) transition metals
(d) Ferrites
Ans C
37. Example for anti-ferro-magnetic materials
(a) salts of transition elements
(b) rare earth elements
(c) transition metals
(d) Ferrites
Ans A
38. Example for ferri-magnetic materials
(a) salts of transition elements
(b) rare earth elements
(c) transition metals
(d) Ferrites
Ans D
39. Magnetic susceptibility para-magnetic materials is
(a) +10-5
(b) -10-5
(c) 105
(d) 10-5 to 10-2
Ans D
40. Magnetic susceptibility dia--magnetic materials is
(a) +10-5
(b) -10-5
(c) 105
(d) 10-5 to 10-2
Ans B
41. Magnetic susceptibility ferro-magnetic materials is
(a) +10-5
(b) -10-5
(c) 105
(d) 10-5 to 10-2
Ans C
42. Typical size of magnetic domains ______ (mm).
(a) 1-10
(b) 0.1-1
(c) 0.05
(d) 0.001
Ans b
43. Typical thickness of Bloch walls ______ (nm).
(a) 0.1-1
(b) 1-10
(c) 10-50
(d) 100
Ans D
44. Example for soft magnet
(a) 45 Permalloy
(b) CrO2
(c) Fe-Pd
(d) Alnico
ANSWER A
45. Example for hard magnet
(a) 45 Permalloy
(b) CrO2
(c) Fe-Pd
(d) Alnico
Ans D
46. Example for magnetic material used in data storage devices
(a) 45 Permalloy
(b) CrO2
(c) Cunife
(d) Alnico
Answers: B
47.In which materials the magnetic anisotropy is followed?
a) Diamagnetic
b) Paramagnetic
c) Ferromagnetic
d) Ferromagnetic
Answer: c
48. The converse of magnetostriction is called the
a) Magnetization
b) Magnetic anisotropy
c) Villari effect
d) Curie effect
Answer: c
49. Which of the following materials is ferrimagnetic?
a) Fe
b) Sn
c) Fe2O3
d) FeCl
Answer: c
50. The line integral of the magnetic field intensity is the
a) Current density
b) Current
c) Magnetic flux density
d) Magnetic moment
Answer: b
51. The equivalent inductances of two coils 2H and 5H in series aiding flux
with mutual inductance of 3H is
a) 10
b) 30
c) 1
d) 13
Answer: d
52. A coil is said to be loosely coupled with which of the following
conditions?
a) K>1
b) K<1
c) K>0.5
d) K<0.5
Answer: d
53. The energy in a magnetic material is due to which process?
a) Emf
b) Magnetization
c) Magnetostriction
d) Polarization
Answer: b
54. The flux lines of two energised coils overlapping on each other will
give
a) Series aiding
b) Shunt aiding
c) Series opposing
d) Shunt opposing
Answer: a
55. A magnetic field exists around
(a) iron
(b) copper
(c) aluminium
(d) moving charges
Ans: d
56. Which of the following is a vector quantity ?
(a) Relative permeability
(b) Magnetic field intensity
(c) Flux density
(d) Magnetic potential
Ans: b
57. The ratio of intensity of magnetisation to the magnetisation force is
known as
(a) flux density
(b) susceptibility
(c) relative permeability
(d) none of the above
Ans: b
58. Magnetising steel is normals difficult because
(a) it corrodes easily
(b) it has high permeability
(c) it has high specific gravity
(d) it has low permeability
Ans: d
59. The unit of relative permeability is
(a) henry/metre
(b) henry
(c) henry/sq. m
(d) it is dimensionless
Ans: d
60. Degaussing is the process of
(a) removal of magnetic impurities
(b) removing gases from the materials
(c) remagnetising metallic parts
(d) demagnetising metallic parts
Ans: d
NEXT PART2.-- https://www.blogger.com/blogger.g?blogID=7785243794411524601#editor/target=post;postID=1240938252735086845;onPublishedMenu=allposts;onClosedMenu=allposts;postNum=2;src=postname
Comments
Post a Comment