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A_Compilati A_Compilation_of_Objective_on_of_Objective_Type_Questions_iType_Questions_in_Electrical_Engin_Electrical_Engineeringneering 1 of 941 of 94CURRENT ELECTRICITYCURRENT ELECTRICITY What are the minimum requirements to cause the flow of current?What are the minimum requirements to cause the f...

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CURRENT ELECTRICITY 1. What What are are the the minimum minimum requirements requirements to to cause cause the the flow flow of of current? current? A. A voltage source, an ammeter, a conductor and an insulator B. A volta age ge source, a switch and a resistor C. A voltage source and a conductor D. A volt voltage age source, a conductor and an insulator 2. Out Out of of the the following, following, select select the the best best conductor conductor of of electricity. electricity. A. A. Graphite B. China clay C. Porcelain

D. None o

3. Which Which of of the the following following statements statements is is correct? correct? A. The The resistance resistance does does not not play play an an important important role role in in electrical electrical engineering. engineering. B. The resistance of a wire does not depend upon its material. C. The resistance of most of tthe he materials is independent of the temperature. D. The resistance of conductor is the hindrance b by y which the conduc flow of the current. 4. Resistance Resistance of of aa conductor conductor increases increases when when A. A. its length increases B. its area increases C. both length and area increases D. specific resistance is kept constant 5. The specific resistance ρdepends upon A. The The area area of of cross-section cross-section and and the the length length of of the the conductor conductor B. The The material material of of the the conductor, conductor, its its area area of of cross-section cross-section and and length length C. The nature of the material of the conducto conductorr only D. The ar area ea of cross-section of the conductor 6. The specific resistance ρis is defined as A. A. resistance of a conductor which has a length of 1 m and cross-sec 20oC B. resistance of any conductor at 25o C C. resistance resistance of of any any conductor conductor at at 20 20o C D. resistance of a conductor which has a length of 1 m and cross-section of 1 c 7. The The resistance resistance of of aa conductor, conductor, when when its its temperature temperature is is increased increased A. remains constant B. increases C. varies D. decreases 8. It It was was experimentally experimentally found found by by James James Prescott Prescott Joule Joule that that the the heat heat produced produced in in a conductor is proportional to A. A. the square of the current B. square of resistance C. the current D. inversely proportional to time

CURRENT ELECTRICITY 10. Temperature Temperature coefficient coefficient of of aa conductor conductor is is defined defined as as the the A. A. increase in resistance per ohm per degree centigrade B. increase in resistance per degree centigrade C. increase in resistance per degree absolute D. decrease in resistance per ohm per degree centi centigrade grade 11. When When current current flows flows in in aa conductor, conductor, heat heat is is produced produced because because 2 A. heat α I B. of electronic collision C. of interatomic collision D. of Joule’s law 12. Heating Heating effect effect of of current current has has undesirable undesirable side side effect effect in in A. electric oven B. electric iron C. immersion heater

D. vacuu

13. The resistance of carbon (filament in carbon-filament lamps) when its temperature i A. A. increases B. decreases C. remains the same D. increases enormously 14. The curve representing Ohm’s law is A. a parabola B. linear

C. sine function

15. The condition in Ohm’s law is that A. ratio V/I should be constant B. current current should should be be proportional proportional to to voltage voltage C. the temperature should remain constant D. the temperature should vary 16. Ohm’s law does not apply to A. conductors B. conductors conductors when when there there is is change change in in temperature temperature C. semiconductor D. a.c. circuit 17. Ohm’s law is applicable to A. electric arc C. gas discharge lamps

B. rectifying devices D. none of these

18. Ohm’s law can be applied with certain reservations to A. rectifying devices B. semiconductors C. electrolytes D. thermionic valves 19. The The presence presence of of an an electric electric current current is is made made known known by by A flashing B effects produced

D. a hype

CURRENT ELECTRICITY 21. The The presence presence of of the the current current isis only only made made known known by by the the effect effect itit produces. produces. Three Three are A. heating, heating, electric electric shock shock and and generation generation B. generation, chemical and electric shock C. heating, magnetic and electric shock D. heating, magnetic and chemical 22. Voltage applied across a circuit, circuit, acts as A. mass of electrons C. a component of current

B. negative ions D. a force

23. In a series circuit the current is A. A. constant C. proportional to the resistance

B. always zero D. different in different resistors

24. In a parallel circuit the potential difference across the resistance A. varies B. is different from the applied vo C. is sometimes constant D. is always constant 25. The resistance R1and and R2are connected in parallel. The ratio of values of resistanc The currents in R1 : R2will will be equal to A. A. 1 : 4 B. 1 : 1 C. 4 : 1 D. 4 : 4 26. A resistance of 4 ohms is connected across 100 V supply. When another res connected connected in in parallel parallel with with 44 ohms, ohms, the the total total current current taken taken from from supply supply was was found found value of resistance ‘R’ is A. 2 ohms B. 3 ohms C. 5 ohms D. 4 ohm 27. The voltage applied across an electric press was reduced by 50%. The power consu will be reduced by A. 25% B. 75% C. 60% D. 50% 28. Two Two electric electric presses presses are are connected connected in in parallel. parallel. The The resistance resistance of of the the first first press press is is 11 of of the the second second isis 300 300 ohms. ohms. The The total total current current taken taken by by both both the the presses presses isis 44 A. A. Th Th taken by first : second will be equal to A. 2 : 3 B. 1 : 3 C. 3 : 1 D. 1.2 : 3 29. Three elements having conductance G 1, G 2  and G3 are connected in parallel. conductance will be 1 A. A. G1+ + G2+ + G3 B. G1 + G 2 + G3 C.

G 1 G 2 + G 2 G3 + G 3G 1 G +G +G

D.

1

1 1

1

CURRENT ELECTRICITY 31. When current flows through heater coil it glows but supply wiring does not glow bec A. supply wiring is covered with insulation layer B. current through supply line flows at slower speed C. supply wires are made of superior material D. resistance of heater coil is more than that of supply wires 32. Resistors commonly used in power circuits are A. carbon resistors C. wire wound resistors

B. etched circuit resistors D. deposited metal resistors

33. International ohm is defined in terms of resistance of A. a column of mercury B. a cube of carbon C. unit length of metal wire D. a cube of copper 34. Which of the following has negative coefficient of resistance? A. wire wound resistor B. non-metals C. thermistor D. metals 35. The current carrying capacity of the fuse material depends on A. length B. material C. cross-sectional area D. all of these

MAGNETISM AND ELECTROMAGNETISM 1. A natural magnet is called A. steel B. lodestone

C. magnetism

2. A magnet is able to attract A. iron, aluminum and brass C. iron, copper and nickel

B. iron, cobalt and zinc D. nickel, cobalt and steel

3. Externally, magnetic line of force travels A. south to north C. negative to positive

B. north to south D. in both directions

4. A material commonly used for shielding or screening magnetism is A. brass B. aluminum C. copper

D. soft iro

D. soft ir

5. The magnetism that remains in a magnet after the magnetizing force has been remo A. permeability B. induction C. residual D. satura 6. Iron becomes magnetized by induction when it is A. heated B. suspended east and west C. near to one end of a magnet D. treated with some chemicals 7. Magnetic lines of force are called A. hysteresis B. current

C. flux

D. magne

8. The force between two magnetic poles varies with distance between them. The vari A. in direct proportion to the distance B. in inverse proportion to the distance C. in direct proportion to the square of the distance D. in inverse proportion to the square of the distance 9. The magnetic potential in a magnetic circuit can be measured in terms of A. farads B. M.M.F. C. coulombs D. none o 10. Permeance is analogous to A. conductance B. resistance

C. reluctance

D. none o

11. The permeability of a material means A. strength of permanent magnet B. strength of an electromagnet C. the magnetization left in the iron after exciting field has been removed D. the conductivity of a material for magnetic lines of force 12. When the magnetic flux (φ) and the area (A) under its influence are known, the ma

MAGNETISM AND ELECTROMAGNETISM 13. The relative permeability µr is given by A. C.

B.

µ0 µ

D.

B H µ0

H

14. Relative permeability of a material is given by (K is susceptibility of the material) A. 1 + µ 0K C. 1 +

µ0

K

B.

+

C.

µ 0H

15. The relative permeability of paramagnetic substance is A. slightly less than 1 B. equal to 1 C. slightly greater than 1 D. very much greater than 1 16. The value of permeability for the free space is A. 4 x 10–7Hm–1 C.

7

–1

4πx 10 Hm

B. 4 x 10–7 Hm–1 1 × 10 − 7Hm −1 D. 4π

17. The magnetization in any magnetic material appears as a result of A. electrons orbital motion B. electron spin C. spin of the nucleus about its axis D. all of these 18. The sum of the magnetic moments in unit volume of the solid is called A. field strength B. magnetization C. permeability D. susceptibility 19. Which of the following materials does not have permanent magnetic dipole A. paramagnetic B. antiferromagnetic C. diamagnetic D. ferrimagnetic 20. Interaction between the neighboring dipoles is negligible in case of a A. paramagnetic material B. diamagnetic material C. antiferromagnetic material D. ferrimagnetic material 21. Each ferromagnetic material has characteristic temperature above which its pro different from those below that temperature. This temperature is called A. transition temperature B. Faraday’s temperature C. demagnetization temperature D. Curie temperature

MAGNETISM AND ELECTROMAGNETISM 24. Which of the following has the highest value of relative permeability µr? A. iron B. supermalloy C. Mu-metal D. 4% Si 25. Ferrimagnetic materials generally behave as a A. semiconductor C. insulator

B. conductor D. any of A, B, or C

26. Transformer cores operating at microwave frequency ranges are generally made up A. ferrites B. silicon steel C. supermalloy D. alnico 27. The magnetic materials which can be easily magnetized in both directions are known A. soft magnetic materials B. hard magnetic materials C. low hysteresis loss materials D. high hysteresis loss materials 28. Eddy current loss can be minimized by A. decreasing the resistance of magnetic medium B. increasing the resistance of magnetic medium C. decreasing the permeability of magnetic medium D. none of the above

ELECTROMAGNETIC INDUCTION 1. The coefficient of self-inductance of a coil is defined as φ A. NI /φ B. C. φ / NI

D.

φI / N

2. Which of the following statement is incorrect? A. Whenever the flux linking with the coil or circuit changes the emf is produce B. The direction of dynamically induced emf can be determined by Flemming’s C. Coefficient of coupling for tightly coupled coil is zero. D. The coefficient of self-inductance is proportional to the square of number of 3. Which of the following statements about inductance of a coil is true? A. Inductance is a characteristic of coil occurring only in case of A.C. B. Inductance appears only if the coil has an iron core. C. Inductance is only another expression for self-induced voltage. D. Inductance characterizes the magnetic properties of a coil which for the value of self-induced voltage generated due to current chan 4. A collapsing field around a coil A. tends to oppose the decay of coil current B. helps the decay of coil current C. tends to aid current flow reversal D. does not affect the coil current flow 5. Energy stored in an inductance is given by A. C.

2LI2 joules Nφ joules I

6. Which of the following is a vector quantity? A. magnetic potential C. magnetic field intensity

B. D.

0 joule joules

B. flux density D. relative permeability

7. A conductor of length L has current I passing through it, when it is placed pa magnetic field. The force experienced by the conductor will be A. BLI B. zero C. B2 LI D. BL2 I 8. Whenever a conductor cuts magnetic flux, an emf is induced in that conductor. This to A. Joule’s law B. Coulomb’s law C. Faraday’s law D. Weber and Ewing’s theory 9. The left hand rule correlates A. self induction, mutual induction and direction of force on a conductor B magnetic field electric field and direction of force on a conductor

ELECTROMAGNETIC INDUCTION 11. The coefficient of coupling between two air core coils depends on A. self inductance of the two coils only B. mutual inductance between the two coils only C. mutual inductance and self inductance of the two coils D. none of the above 12. While comparing magnetic and electric circuits, the flux of magnetic circuit is com parameter of electric circuit? A. e.m.f. B. current density C. conductivity D. current 13. While comparing magnetic and electric circuits, the point of dissimilarity exists while A. flux and current flow B. permeance and conductance C. m.m.f. and e.m.f. D. reluctance and resistance 14. The effect of the inductance of a coil on a constant direct current is that A. it strengthens the current B. it does not affect the constant direct current C. it decreases the current D. it causes a higher voltage drop 15. Good smoothing factor of a coil depends on the A. terminal voltage B. property of the wire of the coil C. inductance of the coil D. cross-sectional area of the wire 16. Leakage factor is A. less than unity C. more than unity

B. equal to unity D. zero

17. The law that induces emf and current always opposes the cause producing them wa A. Lenz B. Faraday C. Maxwell D. Ohm 18. According to Lenz’s law the direction of induced e.m.f. and hence current A. may be found by the right hand rule B. always opposes the cause producing it C. is determined by the rate of cutting flux D. may be found by the left hand rule 19. Sparking occurs when a load is switched off because the circuit has high A. capacitance B. inductance C. resistance D. impeda 20. The flux linked with a coil of inductance Lcarrying current

i

is

d

(Li)

ELECTROMAGNETIC INDUCTION 22. Air gap in the iron core of an inductor prevents A. hysteresis loss B. flux change C. transformer action D. core saturation 23. The growth of current in an inductive circuit follows A. hyperbolic law B. Ohm’s law C. exponential law D. linear law 24. The time constant of an inductive circuit is defined as the ratio of A. R/L B. Rt/L C. Lt/R

D. L/R

25. The time constant is the time it takes the current in an inductive circuit to rise to A. 66% of its final steady state value B. 70% of its final steady state value C. 63% of its final steady state value D. 50% of its final steady state v alue 26. Mutual inductance can also be defined as: A.

=

C.

M = N2

φ di dt

B.

M = N2

D.

M = N2

dt di dt dφ

27. The mutual inductance of two coils is maximum when the coils are A. inclined at an angle of 45 degrees B. at right angle to each other C. facing each other D. touching each other 28. The value of mutual inductance in terms of self inductance of the two coils L1 and to L1 A. L 1L 2 B. L2 C.

D.

L1 L2

29. Coupling coefficient k, a term much used in radio work can be obtained from A. C.

K

= M

L1L 2

=

30. The coupling coefficient denotes A the degree of magnetic linkage

B.

K = M L1 / L 2

D. K= ML1 L2

ELECTROMAGNETIC INDUCTION 32. In electrical machines, laminated cores are used with a view of reducing A. eddy current loss B. copper loss C. hysteresis loss D. windage loss 33. The area of hysteresis loop represents hysteresis loss in 3 B. J/cycle A. J/m /s C. J/s D. J/m3 34. According to Hysteresis law, hysteresis loss in a material is proportional to 1.6 1.2 B. B A. B 0.6 3.6 C. B D. B 35. A degaussing is the process of A. removing gases from materials B. removal of magnetic impurities C. demagnetizing metallic part D. magnetizing nonmetallic part 36. Hysteresis losses can be reduced by A. using grain-oriented silicon steel B. increasing the frequency of the field C. laminating the core D. none of these

ELECTROSTATICS 1. Absolute permittivity of vacuum is taken as A. 8.854 x 10–6 farad/meter –12 B. 8.854 x 10 farad/meter –9 C. 8.854 x 10 farad/meter 12 D. 8.854 x 10 farad/meter 2. Relative permittivity of vacuum is A. zero C. unity

–6

B. 8.854 x 10 farad/meter 9 D. 9 x 10 farad/meter

3. In the electric field, the potential is the work done in joules A. to bring positive charge of one coulomb from infinity to that point B. to bring any charge from infinity to that point C. in moving a unit positive charge from one point to the otherpoint D. to bring any charge from any point to infinity 4. The unit of field intensity is A. coulomb C. newtons/coulomb

2

B. coulomb/m 2 D. newtons/m

5. Coulomb’s law for the force between electric charges most closely resembles with A. Gauss theorem B. Newton’s law of gravitation C. Law of conservation of energy D. Newton’s laws of motion 6. Which of the following equations is correct? A.

∫ Ed l =0

C.

∫ Eds =

B. q

ε0

D.

∫ Eds = q ∫

l

=

→

7. The field F = y i + xj is a A. C.

rotational field conservative field

8. Dielectric strength of a material depends on A. moisture content C. temperature

B. irrotational field D. static electric field

B. thickness D. all of these

9. What will happen to an insulating medium if voltage more than the breakdown volta A. it will get punctured B. it will become magnetic C. it will melt D. its molecular structure will chan 10. Which medium has the highest value of dielectric strength?

ELECTROSTATICS 12. A region around a stationary electric charge has A. electric field B. magnetic field C. both electric and magnetic field D. neither of the two 13. Inside a hollow spherical conductor A. electric field is constant B. electric field is zero C. electric field changes with distance from the center of the sphere D. electric field is unity 14. Capacitors are said to A. block a.c. and pass d.c. C. pass a.c. and d.c.

B. block d.c. and pass a.c. D. block a.c. and d.c.

15. Which statement influences the capacity of a capacitor? A. area of the plates, thickness of the plates and the rate of charge B. area of the plates, dielectric and the r...