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
5101. In a transformer the energy is conveyed from primary to secondary_________?
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A. none of the above

B. by the flux

C. through cooling coil

D. through air

5102. The chemical used in breather is_______________?
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A. asbestos fiber

B. silica sand

C. silica gel

D. sodium chloride

5103. When a given transformer is run at its rated voltage but reduced frequency, its____________?
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A. core flux density is reduced

B. core flux density is increased

C. iron losses are reduced

D. flux density remains unaffected

5104. The purpose of providing an iron core in a transformer is to_____________?
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A. provide support to windings

B. decrease the reluctance of the magnetic path

C. reduce eddy current losses

D. reduce hysteresis loss

5105. Buchholzs relay gives warning and protection against_________________?
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A. electrical fault inside the transformer itself

B. electrical fault outside the transformer in outgoing feeder

C. for both outside and inside faults

D. none of the above

5106. What will happen if the transformers working in parallel are not connected with regard to polarity ?
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A. none of the above

B. The power factor of the two trans-formers will be different from the power factor of common load

C. The transformers will not share load in proportion to their kVA ratings

D. Incorrect polarity will result in dead short circuit
5107. The signal voltage induced in the aerial of a radio receiver is of the order of_____________?
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A. V

B. mV

C. V

D. None of the above

5108. In the above question, what is the power in sidebands ?
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A. 8 kW

B. 6 kW

C. 06 kW

D. 9 kW

5109. The major advantage of FM over AM is__________________?
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A. Smaller bandwidth

B. Reception is less noisy

C. Small frequency deviation

D. Higher carrier frequency

5110. In radio transmission, the medium of transmission is ________________?
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A. None of the above

B. Cable

C. Space

D. An antenna

5111. In TV transmission, sound signal is ______________modulated?
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A. None of the above

B. Phase

C. Frequency

D. Amplitude

5112. The diode detector in an AM radio receiver is usually found _____________?
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A. After several stages of amplification

B. None of the above

C. After the first RF stage

D. Before the first RF stage

5113. In an AM wave useful power is carrier by ______________?
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A. Carrier

B. Sidebands

C. Both sidebands and carrier

D. None of the above

5114. The superhetrodyne principle provides selectivity at ______________stage?
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A. audio

B. Before RF

C. IF

D. RF

5115. The signal voltage induced in the aerial of a radio receiver is of the order of ________________?
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A. V

B. mV

C. None of the above

D. V
5116. In a radio receiver, we generally use .. oscillator as a local oscillator
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A. Phase-shift

B. Hartley

C. Wien-bridge

D. Crystal

5117. As the modulation level is increased, the carrier power__________________?
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A. Is decreased

B. None of the above

C. Is increased

D. Remains the same
5118. Modulation refers to a low-frequency signal controlling the ________________?
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A. May be any of the above

B. Amplitude of the carrier

C. Frequency of the carrier

D. Phase of the carrier

5119. Man made noise are______________ variations?
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A. Amplitude

B. Frequency

C. Phase

D. Both phase and frequency

5120. If level of modulation is increased ______________ power is increased?
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A. Carrier as well as sideband

B. Carrier

C. Sideband

D. None of the above

5121. If a radio receiver amplifies all the signal frequencies equally well, it is said to have high ________________?
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A. Selectivity

B. Sensitivity

C. Fidelity

D. Distortion

5122. If Amin = 40 and Amax = 60, what is the percentage of modulation?
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A. 20 %

B. 50%

C. 40%

D. 10%

5123. In the above question, what is the power in sidebands?
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A. 9 kW

B. 8 kW

C. 6 kW

D. 06 kW
5124. In superhetrodyne receiver, the input at mixer stage is________________?
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A. IF and RF

B. RF and AF

C. IF and AF

D. RF and local oscillator signal
5125. In TV transmission, picture signal is ______________ modulated?
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A. Amplitude

B. Frequency

C. None of the above

D. Phase

5126. Superhertodyne principle refers to_________________?
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A. None of the above

B. Using a large number of amplifier stages

C. Obtaining lower fixed intermediate frequency

D. Using a push-pull circuit

5127. A 100 V carrier is made to vary between 160 V and 40 V by the signal. What is the modulation factor ?
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A. 3

B. None of the above

C. 6

D. 5

5128. A 50 kW carrier is to be amplitude modulated to a level of 85%. What is the carrier power after modulation ?
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A. 5 kW

B. 8 kW

C. 25 kW

D. 50 kW
5129. Most of the amplification in a superhetrodyne receiver occurs at ______________stage?
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A. Detector

B. IF

C. Audio amplifier

D. RF amplifier

5130. In a radio receiver, noise is generally developed at _______________?
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A. Audio stage

B. IF stage

C. RF stage

D. Receiving antenna

5131. The letters AVC stand for ________________?
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A. Audio voltage control

B. Abrupt voltage control

C. Automatic volume control

D. Automatic voltage control

5132. In a TRF radio receiver, the RF and detection stages are tuned to______________?
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A. None of the above

B. IF

C. Audio frequency

D. Radio frequency
5133. The function of ferrite antenna is to_________________?
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A. Reduce noise

B. Increase the Q of tuned circuit

C. Stabilise d.c. bias

D. Reduce stray capacitance

5134. In an AM wave, the majority of the power is in _____________?
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A. Lower sideband

B. Upper sideband

C. None of the above

D. Carrier
5135. When the modulating signal controls the frequency of the carrier, we get______________?
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A. Frequency modulation

B. Phase modulation

C. Amplitude modulation

D. May be any one of the above

5136. In a transmitter ____________oscillator is used?
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A. Wien-bridge

B. Hartley

C. RC phase-shift

D. Crystal
5137. In a superhetrodyne receiver, the difference frequency is chosen as the IF rather than the sum frequency because _________________?
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A. None of the above

B. Only the difference frequency can be modulated

C. The difference frequency is closer to oscillator frequency

D. Lower frequencies are easier to amplify
5138. A high Q tuned circuit will permit an amplifier to have high __________________?
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A. Fidelity

B. Sensitivity

C. Frequency range

D. Selectivity
5139. Demodulation is done in ________________?
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A. Transmitting antenna

B. Transmitter

C. Radio receiver

D. Receiving antenna

5140. The IF is 455 kHz. If the radio receiver is tuned to 855 kHz, the local oscillator frequency is _______________?
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A. 1310 kHz

B. 455 kHz

C. 1520 kHz

D. 1500 kHz

5141. In amplitude modulation, the _____________of carrier is varied according to the strength of the signal?
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A. None of the above

B. Amplitude

C. Frequency

D. Phase

5142. Over modulation results in ______________?
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A. None of the above

B. Weakening of the signal

C. Distortion

D. Excessive carrier power

5143. At 100% modulation, the power in each sideband is _____________ of that of carrier?
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A. 50%

B. 40%

C. 60%

D. 25%
5144. In amplitude modulation, bandwidth is ____________ the audio signal frequency?
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A. Four times

B. Thrice

C. Twice

D. None of the above

5145. If modulation is 100% then signal amplitude is ____________arrier amplitude?
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A. None of the above

B. Greater than

C. Less than

D. Equal to
5146. In pakistan, ______________ modulation is used for radio transmission?
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A. Phase

B. Amplitude

C. Frequency

D. None of the above

5147. Modulation is done in____________________
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A. Radio receiver

B. Transmitter

C. None of the above

D. Between transmitter and radio receiver

5148. Overmodulation (amplitude) occurs when signal amplitude is _____________ carrier amplitude?
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A. Equal to

B. Greater than

C. None of the above

D. Less than

5149. In a D.C. generator the critical resistance can be increased by_____________?
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A. decreasing its speed

B. increasing its field resistance

C. increasing its speed

D. decreasing its field resistance

5150. The open circuit voltage of a compound generator is 250 V. At full load the terminal voltage____________?
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A. may be greater or less than 250 V

B. will be less than 250 V

C. will always be 250 V

D. none of the above