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Mcqs of Transistor which are most important for Electrical and Electronic Engineer. Normally Mcqs of Transistor comes in many technical job tests. these Mcqs of Transistor are prepared for the job seekers which are taken from Books.

Mcqs of Transistor

1. A transistor has ……..
   (i) one pn junction
   (ii) two pn junctions
   (iii) three pn junctions
   (iv) four pn junctions
2. The number of depletion layers in a transistor is ……..
   (i) four (ii) three
   (iii) one (iv) two
3. The base of a transistor is ……. doped.
   (i) heavily (ii) moderately
   (iii) lightly (iv) none of the above
4. The element that has the biggest size in a transistor is ……..
   (i) collector (ii) base
   (iii) emitter
   (iv) collector-base junction
5. In a pnp transistor, the current carriers are……..
   (i) acceptor ions (ii) donor ions
   (iii) free electrons (iv) holes
6. The collector of a transistor is …….. doped.
   (i) heavily (ii) moderately
   (iii) lightly (iv) none of the above
7. A transistor is a ……… operated device.
   (i) current (ii) voltage
   (iii) both voltage and current
   (iv) none of the above
8. In an npn transistor, ……. are the minority carriers.
   (i) free electrons (ii) holes
   (iii) donor ions (iv) acceptor ions
9. The emitter of a transistor is …….. doped.
   (i) lightly (ii) heavily
   (iii) moderately (iv) none of the above
10. In a transistor, the base current is about …….. of emitter current.
    (i) 25% (ii) 20%
    (iii) 35% (iv) 5%
11. At the base-emitter junction of a transistor, one finds ……..

(i) reverse bias
(ii) a wide depletion layer
(iii) low resistance
(iv) none of the above

12. The input impedance of a transistor is ……
    (i) high (ii) low
    (iii) very high (iv) almost zero
13. Most of the majority carriers from the emitter ………
    (i) recombine in the base
    (ii) recombine in the emitter
    (iii) pass through the base region to the collector
    (iv) none of the above
14. The current IB is ……..
    (i) electron current
    (ii) hole current
    (iii) donor ion current
    (iv) acceptor ion current
15. In a transistor, ……..
    (i) IC = IE + IB
    (ii) IB = IC + IE
    (iii) IE = IC− IB
    (iv) IE = IC + IB
16. The value of α of a transistor is ……..
    (i) more than 1 (ii) less than 1
    (iii)1 (iv) none of the above
17. IC= α IE………
    (i) IB
    (ii) ICEO
    (iii) ICBO (iv) β IB
18. The output impedance of a transistor is ……..
    (i) high (ii) zero
    (iii) low (iv) very low
19. In a transistor, IC = 100 mA and IE= 100.5 mA. The value of β is ……..
    (i) 100 (ii) 50
    (iii) about 1 (iv) 200
20. In a transistor if β = 100 and collector current is 10 mA, then IE is ……..
    (i) 100 mA (ii) 100.1 mA
    (iii) 110 mA (iv) none of the above
21. The value of β for a transistor is generally……..
    (i)1 (ii) less than 1
    (iii) between 20 and 500 (iv) above 500
22. The most commonly used transistor arrangement is …….. arrangement.
    (i) common emitter
    (ii) common base
    (iii) common collector
    (iv) none of the above
23. The input impedance of a transistor connected in ………. arrangement is the highest.
    (i) common emitter
    (ii) common collector
    (iii) common base
    (iv) none of the above
24. The output impedance of a transistor connected in ……… arrangement is the highest.
    (i) common emitter
    (ii) common collector
    (iii) common base
    (iv) none of the above
25. The phase difference between the input and output voltages in a common base arrangement is ………
    (i) 180º (ii) 90º
    (iii) 270º (iv) 0º
26. The power gain of a transistor connected in …….. arrangement is the highest.
    (i) common emitter
    (ii) common base
    (iii) common collector
    (iv) none of the above
27. The phase difference between the input and output voltages of a transistor connected in
    common emitter arrangement is ……..
    (i) 0º (ii) 180º
    (iii) 90º (iv) 270º
28. The voltage gain of a transistor connected in …….. arrangement is the highest.
    (i) common base (ii) common collector
    (iii) common emitter (iv) none of the above
29. As the temperature of a transistor goes up, the base-emitter resistance ……..
    (i) decreases (ii) increases
    (iii) remains the same (iv) none of the above
30. The voltage gain of a transistor connected in common collector arrangement is …….
    (i) equal to 1 (ii) more than 10
    (iii) more than 100 (iv) less than 1
31. The phase difference between the input and output voltages of a transistor connected in
    common collector arrangement is ……..
    (i) 180º (ii) 0º
    (iii) 90º (iv) 270º
32. BC 147 transistor indicates that it is made of ……..
    (i) germanium (ii) silicon
    (iii) carbon (iv) none of the above
33. ICEO = (……..) ICBO
    (i) β (ii) 1 + α
    (iii) 1 + β (iv) none of the above
34. A transistor is connected in CB mode. If it is now connected in CE mode with same bias
    voltages, the values of IE, IB and IC will ….
    (i) remain the same
    (ii) increase
    (iii) decrease (iv) none of the above
35. If the value of α is 0.9, then value of β is ……..
    (i)9 (ii) 0.9
    (iii) 900 (iv) 90
36. In a transistor, signal is transferred from a …….. circuit.
    (i) high resistance to low resistance
    (ii) low resistance to high resistance
    (iii) high resistance to high resistance
    (iv) low resistance to low resistance
37. The arrow in the symbol of a transistor indicates the direction of ………
    (i) electron current in the emitter
    (ii) electron current in the collector
    (iii) hole current in the emitter
    (iv) donor ion current
38. The leakage current in CE arrangement is ……. that in CB arrangement. (i) more than (ii) less than (iii) the same as (iv) none of the above
39. A heat sink is generally used with a transistor to ……..
    (i) increase the forward current
    (ii) decrease the forward current
    (iii) compensate for excessive doping
    (iv) prevent excessive temperature rise
40. The most commonly used semiconductor in the manufacture of a transistor is …….. (i) germanium (ii) silicon (iii) carbon (iv) none of the above
41. The collector-base junction in a transistor has ……..
    (i) forward bias at all times
    (ii) reverse bias at all times
    (iii) low resistance
    (iv) none of the above

Chapter Review Topics of Transistor

1. What is a transistor ? Why is it so called ?
2. Draw the symbol of npn and pnp transistor and specify the leads.
3. Show by means of a diagram how you normally connect external batteries in (i) pnp transistor (ii) npn transistor.
4. Describe the transistor action in detail.
5. Explain the operation of transistor as an amplifier.
6. Name the three possible transistor connections.
7. Define α. Show that it is always less than unity.
8. Draw the input and output characteristics of CB connection. What do you infer from these characteristics ?
9. How will you determine the input and output characteristics of CE connection experimentally
10. How will you draw d.c. load line on the output characteristics of a transistor ? What is its importance?
11. Explain the following terms : (i) voltage gain (ii) power gain (iii) effective collector load.
12. Write short notes on the following : (i) advantages of transistors (ii) operating point (iii) d.c. load line.

Problems of Transistor

1. In a transistor if IC = 4.9mA and IE = 5mA, what is the value of α ? [0.98]
2. In a transistor circuit, IE = 1mA and IC = 0.9mA. What is the value of IB? [0.1 mA]
3. Find the value of β if α = 0.99. [100]
4. In a transistor, β = 45, the voltage across 5kΩ resistance which is connected in the collector circuit is 5 volts. Find the base current. [0.022 mA]
5. In a transistor, IB = 68 µA, IE = 30 mA and β = 440. Find the value of α. Hence determine the value of IC. [0.99 ; 29.92 mA]
6. The maximum collector current that a transistor can carry is 500 mA. If β = 300, what is the maximum allowable base current for the device ? [1.67 mA]
7. For the circuit shown in Fig. 8.69, draw the d.c. load line.

8. Draw the d.c. load line for Fig. 8.70. [The end points of load line are 6.06 mA and 20 V]

9. If the collector resistance RC in Fig. 8.70 is reduced to 1 kΩ, what happens to the d.c. load line? [The end points of d.c. load line are now 20 mA and 20 V]
10. Draw the d.c. load line for Fig. 8.71. [The end points of d.c. load line are 10.6 mA and 5V]
11. If the collector resistance RC in Fig. 8.71 is increased to 1 kΩ, what happens to the d.c. load
    line ? [The end points of d.c. load line are now 5 mA and 5 V]

12. Determine the intercept points of the d.c. load line on the vertical and horizontal axes of the
    collector curves in Fig. 8.72. [2 mA ; 20 V]
13. For the circuit shown in Fig. 8.73, find (i) the state of the transistor and (ii) transistor power.
    [(i) active (ii) 4.52 mW]

14. A base current of 50 µA is applied to the transistor in Fig. 8.74 and a voltage of 5V is
    dropped across RC. Calculate α for the transistor. [0.99]
15. A certain transistor is to be operated at a collector current of 50 mA. How high can VCE go without exceeding PD (max) of 1.2 W ? [24 V]

Discussion Questions of Transistor

1. Why is a transistor low powered device ?
2. What is the significance of arrow in the transistor symbol ?
3. Why is collector wider than emitter and base ?
4. Why is collector current slightly less than emitter current ?
5. Why is base made thin ?

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