electrical engineering Mcqs
1. economics of power generation2. analog electronics3. solid state switching circuits4. parallel circuits5. switchgear and protection6. op amp circuits7. transistor audio power amplifiers8. electrostatics9. heating and welding10. multi stage transistor amplifiers11. passive filters12. network theorems13. regulated d c power supply14. a c fundamentals circuits and circuit theory15. electromagnetic induction16. power electronics17. magnetism and electromagnetism18. transformers19. modulation and demodulation20. d c generators21. semiconductor theory22. single phase induction motors23. semiconductor diode24. hybrid parameters25. digital electronics26. oscillators27. earthing or grounding28. single stage transistor amplifiers29. d c motors30. transistor biasing31. amplifiers with negative feedback32. basic electrical33. electronic instruments34. synchronous motors35. field effect transistors fet36. magnetic circuit37. control systems38. industrial drives39. power generation40. series parallel circuits41. transistor tuned amplifiers42. electrical engineering materials43. rectifiers and converters44. integrated circuits45. scr silicon controlled rectifiers46. cables47. polyphase induction motors48. measurement and instrumentation49. transistors50. electrical machine design51. electrolysis and storage of batteries52. electric traction53. transmission and distribution
6551. The photo-electric effect occurs only when the incident light has more than a certain critical____________?
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A. speed

B. wave length

C. frequency

D. intensity

6552. The resistivity of a metal is a function of temperature because_____________?
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A. the electron density varies with temperature

B. the amplitude of vibration of the atoms varies with temperature

C. the electron gas density varies with temperature

6553. In conductors conduction of electricity takes place due to movement of_______________?
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A. negative ions only

B. electrons only

C. none of the above

D. positive and negative ions

E. positive ions only

6554. Piezoelectric materials serve as a source of ____________ ?
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A. resonant waves

B. ultrasonic waves

C. musical waves

D. microwaves

6555. Which of the following high resistance materials has the highest operating temperature ?
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A. Kanthal

B. Eureka

C. Nichrome

D. Manganin

6556. The transition temperature of mercury is____________?
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A. 4.12K

B. 9.22K

C. 1.14K

D. 18.0K

6557. Overhead telephone wires are made of_____________?
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A. steel

B. ACSR conductors

C. aluminium

D. copper

6558. Which of the following variety of copper has the best conductivity ?
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A. Pure annealed copper

B. Hard drawn copper

C. Induction hardened copper

D. Copper containing traces of silicon

6559. Constantan contains_______________?
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A. copper and nickel

B. tungsten and silver

C. copper and tungsten

D. silver and tin

6560. The tiny block formed by the arrangement of a small group of atoms is called the____________?
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A. either A. or (b)

B. none of the above

C. space lattice

D. unit cell
6561. The conductivity of an extrinsic semiconductor with temperature________________?
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A. increases

B. decreases

C. remains constant
6562. The structure sensitive property of a super conductor is______________?
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A. transition temperature

B. critical current density

C. none of the above

D. critical magnetic field

6563. The coils of D.C. motor starter are wound with wire of_______________?
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A. kanthal

B. copper

C. nichrome

D. manganin
6564. Which of the following factors affect resistivity of metals ?
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A. Age hardening

B. Alloying

C. All of the above

D. Temperature

E. Cold work

6565. In a superconductor the value of critical density depends upon______________?
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A. magnetic field strength

B. temperature

C. either (A) or (B)

D. both (A) and (B)
6566. An H.R.C. fuse is_______________?
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A. a wire of platinum

B. a ceramic tube having carbon rod inside it

C. a ceramic body having metal and caps

D. a heavy cross-section of copper or aluminium

6567. Due to which of the following reasons copper and aluminium are not used for heating elements ?
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A. Both have great tendency for oxidation

B. Both have low melting point

C. Very large length of wires will be required

D. All of the above
6568. The carbon percentage is least in__________________?
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A. wrought iron

B. malleable iron

C. cast iron

D. low carbon steel

6569. Superconducting metal in super conducting state has relative permeability of________________?
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A. one

B. more than one

C. negative

D. zero
6570. Which of the following materials does not have covalent bonds ?
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A. Silicon

B. Organic polymers

C. Metals
6571. Which of the following affect greatly the resistivity of electrical conductors ?
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A. Size

B. Pressure

C. Composition

D. Temperature

6572. ___________ is most commonly used for making magnetic recording tape?
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A. Ferric oxide

B. Silver nitrate

C. Silicon-iron

D. Small particles of iron

6573. Low resistivity materials are used in__________?
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A. transformer, motor and generator windings

B. transmission and distribution lines

C. house wiring

D. all above applications
6574. Superconductivity is observed for____________?
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A. none of the above

B. a.c. and high frequency

C. frequencies having no effect

D. infrared frequencies

E. d.c. and low frequency
6575. Which of the following resistive materials has the lowest temperature co-efficient of resistance ?
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A. Constantan

B. Molybdenum

C. Kanthal

D. Nichrome
6576. Effect of moisture on the insulating materials is to________________?
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A. all of the above

B. decrease dielectric constant

C. increase dielectric loss

D. decrease insulation resistance

E. decrease dielectric strength

6577. Super conductivity can be destroyed by_____________?
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A. any of the above

B. reducing temperatures

C. application of magnetic field

D. adding impurities

6578. Substances whose specific resistance abruptly decreases at very low temperature are called___________?
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A. conductors

B. semiconductors

C. insulators

D. superconductors
6579. is a negatively charged particle present in an atom______________?
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A. Electron

B. Proton

C. Neutron

D. None of the above

6580. The formula __________ determines the number of electrons that can be accommodated in any level?
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A. 4ns

B. 2n3

C. 4n2

D. 2n2
6581. For germanium the forbidden energy gap is_______________?
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A. 0.15 eV

B. 0.7eV

C. 0.25 eV

D. 0.5eV

6582. The metal having the lowest temperature coefficient of resistance is_________________?
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A. aluminium

B. gold

C. copper

D. kanthal

6583. Carbon rods are used in wet and dry cells because_____________?
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A. carbon rod serves as conductor

B. carbon can resist the attack of battery acid

C. both (A) and (B)

D. either (A) or (B)

6584. Carbon electrodes are not used in_______________?
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A. electric arc furnace

B. GLS lamps

C. dry cells

D. cinema projectors

6585. Which of the following materials is the best conductor of electricity ?
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A. Carbon

B. Copper

C. Tungsten

D. Aluminium

6586. In a rotary converter I2R losses as compared to a D.C. generator of the same size will be___________?
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A. three times

B. less

C. double

D. same

6587. In a mercury arc rectifier characteristic blue luminosity is due to_____________?
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A. electron streams

B. high temperature

C. colour of mercury

D. ionization
6588. Selenium rectifier can be operated at temperatures as high as____________?
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A. 25C

B. 60C

C. 75C

D. 40C

6589. In a mercury arc rectifier, the anode is usually made of_____________?
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A. copper

B. tungsten

C. aluminium

D. graphite

E. silver

6590. A commutating rectifier consists of commutator driven by___________?
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A. a D.C. series motor

B. a synchronous motor

C. an induction motor

D. a D.C. shunt motor

6591. A rotary converter in general construction and design, is more or less like___________?
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A. an alternator

B. any D.C. machine

C. a transformer

D. an induction motor

6592. In which of the following appUcations, direct current is absolutely essential ?
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A. Variable speed operation

B. Electrolysis

C. Illumination

D. Traction

6593. In a mercury arc rectifier________ flow from anode to cathode
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A. ions

B. any of the above

C. ions and electrons

D. electrons

6594. The ionization potential of mercury is approximately_____________?
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A. 5.4 V

B. 10.4 V

C. 16.4 V

D. 8.4 V

6595. In mercury arc rectifiers having grid, the arc can be struck between anode and cathode only when the grid attains a certain potential, this potential being known as______________?
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A. maximum grid voltage

B. critical grid voltage

C. none of the above

D. any of the above

6596. The efficiency of the copper oxide rectifier seldom exceeds____________?
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A. 80 to 85%

B. 90 to 95%

C. 85 to 90%

D. 65 to 75%
6597. To produce cathode spot in a mercury arc rectifier______________?
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A. low mercury vapour pressures are used

B. anode is heated

C. an auxiliary electrode is used

D. tube is evacuated

6598. In a glass bulb mercury arc rectifier the maximum current rating is restricted to___________?
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A. 1500 A

B. 500 A

C. 2000 A

D. 1000 A

6599. The applications of selenium rectifiers are usually limited to potential of_____________?
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A. 200 V

B. 10 V

C. 30 V

D. 100 V

E. 60 V

6600. With a motor converter it is possible to obtain D.C. voltage only upto__________?
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A. 200-100 V

B. 10001200 V

C. 17002000 V

D. 600800 V