EC
Engineering Classroom
by Himalay Sen

Exams

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Board Questions

Access past board exam questions organized by year and subject to help you understand patterns, improve preparation, and boost your exam performance.

MCQ
41. A PN junction acts as a--
unidirectional switch
bidirectional switch
controlled switch
none of the above
ব্যাখ্যা: ব্যাখ্যা: The PN junction is conduct with forward bias only. It means they conduct in only one direction (Current flows from P to N) That's why PN Junction acts as unidirectional twitch
42. If, line frequency is 50 Hz, then output (Hz) of a bridge rectifier is-
25
100
50
None
ব্যাখ্যা: ব্যাখ্যা: Output frequency of bridge rectifier is twice the input frequency. Full wave bridge rectifier, 25,2x50=100H
48. Process of adding impurities to semiconductor is called-
mixing
refining
diffusing
doping
ব্যাখ্যা: ব্যাখ্যা: The process of adding controlled inpurities to a semiconductor is known as "doping" The amount of impurity, or dopant, added to as intrinsic (pure) semiconductor varies its level of conductivity.
49. In an LC oscillator, the frequency of oscillation is:
Proportional to LC
Proportional to square root of LC
Inversely proportional to the square root of LC
Independent of the value of LC
52. For highest power gain, one would use-- configuration.
CE
CB
CC
none of these
ব্যাখ্যা: ব্যাখ্যা: For highest power gain, CE configuration is used. In CE configuration, biasing capacitor is used to balance the operating point to obtain highest power gain
54. Which one is the smallest region in a transistor?
base
collector
emitter
both (a) and (b)
ব্যাখ্যা: ব্যাখ্যা: The base region of a BJT transistor is very thin and is lightly doped with current carries. It is the region of a transistor which has opposite polarity charge carries from the emitter and the collector regions.