• January 28, 2022

Physics MCQ on BJT (Bipolar Junction Transistors) for NEET, JEE, Medical and Engineering Exam 2021

MCQ on BJT (Bipolar Junction Transistors): Previous trends reveal that NEET/JEE aspirants find Physics as the most challenging section amongst the other sections. But most of them fail to decipher the reason behind this. This particularly can be as the candidates taking up this examination are predominantly medical aspirants with their subject of interest being Biology. Also, sections like Physics are more on theories, laws, numerical as opposed to Biology which is more of fact-based, life sciences and comprising of substantial explanations.


In this post we are providing you MCQ on BJT, which will be beneficial for you in upcoming NEET, AIIMS, JEE, WBJEE, Medical and Engineering Exams.



Q1. When zero input control signal is applied which functional mode enables the BJT to act as an open switch?
a) Reversed biased mode of BE junction
b)  Reversed as well as forward- biased mode of BE junction
c) Forward  biased mode of BE junction
d) None

View Answer

(d) None

Q2. For the second approximation what is the base-emitter voltage?
a) 0.3 V
b) 0.7 V
c) 0
d) 1V

View Answer

(b) 0.7V

Q3. Which of the following leakage current causes a small collector current with zero base current
a) Collector diode
b) Base diode
c) Emitter diode
d) Transistor

View Answer

(a) collector diode

Q4. Will a transistor act as a closed switch by defining the requisite magnitude of saturation level with an equivalent amount of 
a) negative control voltage
b) both negative and positive control voltage  
c) positive control voltage
d) none of the above

View Answer

(a) Positive control voltage

Q5. For a transistor to operate in an active region what is the essential possible condition of biasing
a) Collector-base and emitter-base junctions are reverse biased.
b) Collector-base  junction is reverse biased and the emitter-base is forward biased
c) Collector-base  and emitter-base junctions are forward biased
d) Collector-base  junction is forward biased  and emitter-base is reverse biased

View Answer

(b) Collector-base junction is reverse biased and the emitter-base is forward biased

Q6. What is the collector current when the base resistor is open?
a) 1mA
b) 2mA
c) 0
d) 10mA

View Answer


Q7. Which operating region of BJT enables Emitter-base & collector-base junctions to undergo perfect short-circuit configuration?
a) Saturation Region
b) Cut-off Region
c) Active Region
d) None

View Answer

(a) Saturation Region

Q8. What will be the answer if we recalculate the collector-emitter voltage with the second approximation?
a) The same as the ideal value
b) Larger than the ideal value
c) Smaller than the ideal value
d) Incorrect

View Answer

(b) Larger than the ideal value

Q9. The power dissipated by a transistor approximately equals the collector current times.
a) Collector – emitter voltage
b) Base – emitter voltage
c) Base supply voltage
d) 0.7 V

View Answer

(a) Collector – emitter voltage

Q10. Which current source is connected between collector and base terminals in order to supervise the consequences of base control in an active region DC Model of BJT?
a) αIB
b) βIB
c) αIE
d) βIE

View Answer

(b) βIB


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By Team Learning Mantras