This set of Electronic Devices and Circuits Multiple Choice Questions & Answers (MCQs) focuses on “The Junction Transistor”.
1. The advantages over the vacuum triode for a junction transistor is_________
a) high power consumption
b) high efficiency
c) large size
d) less doping
Explanation: A junction transistor is an analogous to a vacuum triode. The main difference between them is that a transistor is a current device while a vacuum triode is a voltage device. The advantages of a transistor over a vacuum triode are long life, high efficiency, light weight, smaller in size, less power consumption.
2. What is the left hand section of a junction transistor called?
d) depletion region
Explanation: The main function of this section is to supply majority charge carriers to the base. Hence it is more heavily doped in comparison to other regions. This forms the left hand section of the transistor.
3. In an NPN transistor, the arrow is pointed towards_________
a) the collector
b) the base
c) depends on the configuration
d) the emitter
Explanation: As regards to the symbols, the arrow head is always at the emitter. The direction indicates the conventional direction of current flow. In case of PNP transistor, it is from base to emitter.
4. Which of the following is true in construction of a transistor?
a) the collector dissipates lesser power
b) the emitter supplies minority carriers
c) the collector is made physically larger than the emitter region
d) the collector collects minority charge carriers
Explanation: In most of the transistors, the collector is made larger than emitter region. This is due to the fact that collector has to dissipate much greater power. The collector and emitter cannot be interchanged.
5. In the operation of an NPN transistor, the electrons cross which region?
a) emitter region
b) the region where there is high depletion
c) the region where there is low depletion
d) P type base region
Explanation: The electrons in the emitter region are repelled by the negative terminal of the battery towards the emitter junction. The potential barrier at the junction is reduced due to forward bias and base region is very thin and lightly doped, electrons cross the P type base region.
6. Which of the following are true for a PNP transistor?
a) the emitter current is less than the collector current
b) the collector current is less than the emitter current
c) the electrons are majority charge carriers
d) the holes are the minority charge carriers
Explanation: The 2 – 5% of holes is lost in recombination with electrons in the base region. The majority charge carriers are holes for a PNP transistor. Thus the collector current is slightly less than the emitter current.
7. In the saturated region, the transistor acts like a_________
a) poor transistor
c) open switch
d) closed switch
Explanation: In saturated mode, both emitter and collector are forward biased. The negative of the battery is connected to emitter and similarly the positive terminals of batteries are connected to the base. The transistor now acts like a closed switch.
8. When does the transistor act like an open switch?
a) cut off region
b) inverted region
c) saturated region
d) active region
Explanation: In cut off region, both the junctions are reverse biased. The transistor has practically zero current because the emitter does not emit charge carriers to the base. So, the transistor acts as open switch.
9. If the emitter-base junction is forward biased and the collector-base junction is reverse biased, what will be the region of operation for a transistor?
a) cut off region
b) saturated region
c) inverted region
d) active region
Explanation: When the emitter-base junction is forward biased and the collector-base junction is reverse biased, the transistor is used for amplification. A battery is connected to collector base circuit. The positive terminal is connected to the collector while the negative is connected to the base.
10. The transfer of a signal in a transistor is_________
a) low to high resistance
b) high to low resistance
c) collector to base junction
d) emitter to base junction
Explanation: A forward biased emitter base junction has a low resistance path. A reversed biased junction has a high resistance path. The weak signal is introduced in a low resistance circuit and the output is taken from the high resistance circuit.
Sanfoundry Global Education & Learning Series – Electronic Devices and Circuits.
To practice all areas of Electronic Devices and Circuits, here is complete set of 1000+ Multiple Choice Questions and Answers.