electrical engineering Mcqs
2451. ___________ has the best damping properties?
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A. Diamond

B. Cast iron

C. High speed steel

D. Mild steel

2452. In TV transmission, sound signal is ______________modulated?
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A. Amplitude

B. Phase

C. None of the above

D. Frequency
2455. The conductors have transport phenomena of electrons due to____________?
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A. electric field

B. electromagnetic field

C. none of the above

D. magnetic field

2456. The normal way to turn on a SCR is by______________?
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A. Appropriate anode current

B. Breakover voltage

C. Appropriate gate current

D. None of the above

2457. The conduction of electricity, in semiconductors, takes place due to movement of______________?
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A. positive ions only

B. positive and negative ions

C. electrons and holes

D. negative ions only

2458. A highly conductive material must have___________?
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A. good corrosion resistance

B. lowest temperature co-efficient

C. good mechanical strength

D. all of the above

E. easy solderable and drawable quality

F. highest conductivity

2459. The superconductivity is due to____________?
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A. none of the above

B. the electrons jump into nucleus at 0K

C. the crystal structure having no atomic vibration at 0K

D. all electrons interact in the super-conducting state

2460. An SCR is sometimes called ____________?
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A. Thyristor

B. Triac

C. Unijunction transistor

D. Diac

2464. Which of the following is the major consideration to evolve a good design ?
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A. Durability

B. Compliance with performance criteria as laid down in specifications

C. All of the above

D. Cost

2465. _____________is viscoelastic?
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A. Rubber

B. Glass

C. Cast-iron

D. Graphite

2466. An SCR is a solid state equivalent of ______________?
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A. Gas-filled triode

B. Triode

C. Tetrode

D. Pentode

2468. At series resonance, voltage across L is____________voltage across C?
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A. Less than but in phase with

B. Greater than but in phase with

C. Equal to but opposite in phase to

D. Equal to but in phase with

2469. The minority carrier concentration is largely a function of_____________?
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A. the amount of doping

B. temperature

C. reverse biasing voltage

D. forward biasing voltage

2472. An SCR is made of_______________?
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A. Silicon

B. Carbon

C. None of the above

D. Germanium

2473. An SCR has three terminals viz ________________?
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A. Cathode, anode, gate

B. Anode, cathode, drain

C. Anode, cathode, grid

D. None of the above

2474. Piezoelectric materials serve as a source of ____________ ?
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A. musical waves

B. ultrasonic waves

C. resonant waves

D. microwaves

2475. An SCR combines the features of ____________?
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A. A rectifier and capacitor

B. A rectifier and transistor

C. None of the above

D. A rectifier and resistance

2478. Thermonic emission occurs in______________?
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A. ferrite cores

B. vacuum tubes

C. transistors

D. copper conductors

2479. The value of critical field below the transition temperature will_______________?
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A. remain unchanged

B. decrease

C. increase

D. any of the above

2481. Man made noise are______________ variations?
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A. Amplitude

B. Frequency

C. Phase

D. Both phase and frequency

2482. At parallel resonance, the ratio L/C is ______________?
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A. Small

B. None of the above

C. Zero

D. Very large
2483. Demodulation is done in ________________?
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A. Transmitting antenna

B. Receiving antenna

C. Transmitter

D. Radio receiver
2484. Overhead telephone wires are made of_____________?
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A. ACSR conductors

B. aluminium

C. steel

D. copper

2486. If the resistance of a conductor does not vary in accordance with Ohms law it is known as____________?
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A. reverse conductor

B. non-conductor

C. non-linear conductor

D. bad-conductor

2487. In a parallel LC circuit, if the signal frequency is decreased below the resonant frequency, then________________?
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A. XL decreases and XC increases

B. Line current becomes minimum

C. XL increases and XC decreases

D. None of the above

2489. An SCR is turned off when ________________?
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A. Gate is reverse biased

B. Gate voltage is reduced to zero

C. Anode current is reduced to zero

D. None of the above

2490. 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)

2491. In normal operation of an SCR, gate is _____________w.r.t. cathode?
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A. None of the above

B. Positive

C. Negative

D. At zero potential

2492. If modulation is 100% then signal amplitude is ____________arrier amplitude?
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A. Greater than

B. Less than

C. None of the above

D. Equal to
2493. For a hole which of the following statements is incorrect ?
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A. Holes may constitute an electric current

B. Holes can exist in certain semiconductors only

C. Holes can be considered as a net positive charge

D. Holes can exist in any material including conductors
2494. Modulation is done in____________________
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A. None of the above

B. Radio receiver

C. Transmitter

D. Between transmitter and radio receiver

2495. In TV transmission, picture signal is ______________ modulated?
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A. Frequency

B. None of the above

C. Phase

D. Amplitude
2496. In the above question, what are the values of cut-off frequencies?
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A. None of the above

B. 1030 kHz , 970 kHz

C. 140 kHz , 60 kHz

D. 1020 kHz , 980 kHz
2497. Tuned class C amplifiers are used for RF signals of________________?
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A. Low power

B. Very high power

C. None of the above

D. High power

2499. Superconductivity is observed for____________?
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A. a.c. and high frequency

B. none of the above

C. frequencies having no effect

D. d.c. and low frequency

E. infrared frequencies