Transistors – Exercise – 1

1. A transistor acts as a :

(a)  Diode and voltage source
(b)  Diode and current source
(c)  Diode and power supply
(d)  Diode and resistance

Answer
Answer : (b)
Explanation
No answer description available for this question. Let us discuss.
2. The free electrons recombine with a hole in the base region of a transistor to become :

(a)  Free electrons
(b)  Valence electrons
(c)  Atom
(d)  Majority carrier

Answer
Answer : (b)
Explanation
No answer description available for this question. Let us discuss.
3. Transistor is a :

(a)  current controlled current device
(b)  current controlled voltage device
(c)  voltage controlled current device
(d)  voltage controlled voltage device

Answer
Answer : (a)
Explanation
No answer description available for this question. Let us discuss.
4. ICBO in a transistor can be reduced by :

(a)  Reducing IB
(b)  Reducing VCC
(c)  Reducing IE
(d)  Reducing the temperature

Answer
Answer : (d)
Explanation
No answer description available for this question. Let us discuss.
5. The base current of a transistor is typically :

(a)  Less than emitter current
(b)  Greater than emitter current
(c)  Same as emitter current
(d)  Equal to the sum of emitter and collector currents

Answer
Answer : (a)
Explanation
No answer description available for this question. Let us discuss.
6. The current gain of a transistor is :

(a)  The ratio of collector current to emitter current
(b)  The ratio of collector current to base current
(c)  The ratio of base current to collector current
(d)  The ratio of emitter current to collector current

Answer
Answer : (b)
Explanation
No answer description available for this question. Let us discuss.
7. The most commonly used configuration of transistor as switch is :

(a)  CB
(b)  CC
(c)  CE
(d)  CB or CC

Answer
Answer : (c)
Explanation
No answer description available for this question. Let us discuss.
8. When an N-P-N transistor is used as an amplifier then :

(a)  Electrons move from base to collector
(b)  Electrons move from emitter to base
(c)  Electrons move from collector to base
(d)  Holes move from base to emitter

Answer
Answer : (a)
Explanation
No answer description available for this question. Let us discuss.
9. The free electrons have ___ in the base region of a transistor.

(a)  Short lifeterm
(b)  Long lifeterm
(c)  No lifeterm at all
(d)  Infinite lifeterm

Answer
Answer : (a)
Explanation
No answer description available for this question. Let us discuss.
(a) (b) (c) (d) Answer : () [/su_spoiler]
Explanation
No answer description available for this question. Let us discuss.
(a) (b) (c) (d) Answer : () [/su_spoiler]
Explanation
No answer description available for this question. Let us discuss.
12. The α of the transistor is :

(a)  A measure of its sensitivity
(b)  A measure of quality
(c)  A measure of thermal stability
(d)  A measure of its noise immunity

Answer
Answer : (b)
Explanation
No answer description available for this question. Let us discuss.
13. Normal biasing of transistor is :

(a)  Forward bias the Emitter-Base and reverse bias the Collector-Base
(b)  Forward bias both the Emitter-Base and Collector-Base
(c)  Reverse bias both the Emitter-Base and Collector-Base
(d)  Reverse bias both Emitter-Base and forward bias the Collector-Base

Answer
Answer : (a)
Explanation
No answer description available for this question. Let us discuss.
14. With reference to the current amplification factor of transistor :

(a)  α is greater than β
(b)  α is smaller than β
(c)  α and β are equal
(d)  None of the above

Answer
Answer : (b)
Explanation
No answer description available for this question. Let us discuss.
15. When a transistor is connected in common collector mode, then

(a)  Input is in between Base and Emitter
(b)  Input is in between Base and Collector
(c)  Input is in between Emitter and Collector
(d)  Input is in between Collector short-circuited

Answer
Answer : (b)
Explanation
No answer description available for this question. Let us discuss.
16. In a transistor, if the base current is 1 mA and collector current is 2 mA, then :

(a)  IE = 1 mA
(b)  IE = 2 mA
(c)  IE = 3 mA
(d)  IE = 4 mA

Answer
Answer : (c)
Explanation
No answer description available for this question. Let us discuss.
17. The β value of a transistor can be determined from the curve plotted between :

(a)  VBE and IE for constant VCE
(b)  VBE and IC for constant VCE
(c)  VCE and IE for constant IB
(d)  VCE and IC for constant IB

Answer
Answer : (d)
Explanation
No answer description available for this question. Let us discuss.
18. The DC current gain of a transistor is :

(a)  Always positive and greater than unity
(b)  Always positive and less than unity
(c)  Always positive and equal to unity
(d)  Always positive and equal to infinity

Answer
Answer : (b)
Explanation
No answer description available for this question. Let us discuss.
19. The Collector to Base with Emitter open current, a transistor is extremely temperature dependent because :

(a)  It is made up of free electrons and holes
(b)  It is made up of thermally generated majority carrier
(c)  It is made up of thermally generated minority carrier
(d)  It is made up of free electrons alone

Answer
Answer : (c)
Explanation
No answer description available for this question. Let us discuss.
20. For N-P-N transistor the value of β in common base is 100. The value of current gain α in common emitter is –

(a)  0.99
(b)  0.92
(c)  1.01
(d)  0.95

Answer
Answer : (a)
Explanation
No answer description available for this question. Let us discuss.
21. Localized hot spots and device destruction can take place in power transistors due to :

(a)  Avalanche breakdown
(b)  Primary breakdown
(c)  Second breakdown
(d)  Quasi-saturation breakdown

Answer
Answer : (c)
Explanation
No answer description available for this question. Let us discuss.
22. The current amplification factor of α of a transistor is always :

(a)  Less than 1
(b)  Greater than 1
(c)  Equal to 1
(d)  None of these

Answer
Answer : (a)
Explanation
No answer description available for this question. Let us discuss.
23. As compared to PNP transistor, NPN transistors are preferred due to :

(a)  Economical
(b)  Simple operating mechanism
(c)  Consumes less bias voltage
(d)  Better high frequency response

Answer
Answer : (d)
Explanation
No answer description available for this question. Let us discuss.
24. Two elements that are frequently used for making transistors are :

(a)  Iridium and Tungsten
(b)  Lead and Tin
(c)  Iron and Carbon
(d)  Silicon and Germanium

Answer
Answer : (d)
Explanation
No answer description available for this question. Let us discuss.
25. The current in a PMOS transistor is :

(a)  Less than thrice that in an NMOS device
(b)  Greater than thrice that in a PMOS device
(c)  Less than half of that in an NMOS device
(d)  Greater than half of that in a WMOS device

Answer
Answer : (c)
Explanation
No answer description available for this question. Let us discuss.
26. The turn-on time of a typical transistor is equal to :

(a)  Delay time
(b)  Rise time
(c)  Storage time
(d)  Sum of delay time & rise time

Answer
Answer : (d)
Explanation
No answer description available for this question. Let us discuss.
27. Match list 1 with list 2 with respect to transistor biasing Biasing Region of operation
(A) When EB & CB junctions are forward biased                   (1) Inverted
(B) When EB & CB junctions are reverse biased                    (2) Cut-off
(C) When EB is forward biased & CB is reverse biased         (3) Active
(D) When EB is reverse & CB is forward biased                     (4) Saturation

(a)  A-1, B-2, C-3, D-4
(b)  A-4, B-2, C-3, D-1
(c)  A-4, B-3, C-2, D-1
(d)  A-4, B-1, C-3, D-2

Answer
Answer : (b)
Explanation
No answer description available for this question. Let us discuss.
28. Which is the largest transistor current ?

(a)  Emitter current
(b)  Base current
(c)  Collector current
(d)  Both Emitter & Collector currents

Answer
Answer : (a)
Explanation
No answer description available for this question. Let us discuss.
29. Transistor is said to be in a quiescent state when :

(a)  It is unbiased
(b)  No current flows through it
(c)  No signal is applied to its input
(d)  Emitter junction is reverse biased

Answer
Answer : (c)
Explanation
No answer description available for this question. Let us discuss.
30. Which of the following statements is/are correct ?

(a)  Two discrete diodes connected back-to-back can work as a transistor
(b)  Heat sink is a sheet of insulator used todissipate the heat developed at the collector junction of a power transistor
(c)  The collector leakage current is strongly independent of temperature
(d)  The collector junction of transistor is heavily doped

Answer
Answer : (b)
Explanation
No answer description available for this question. Let us discuss.
31. The transistor was invented at Bell Laboratories in 1947 by :

(a)  John Bardeen
(b)  Walter Brattain
(c)  William Shockley
(d)  All of the above

Answer
Answer : (d)
Explanation
No answer description available for this question. Let us discuss.
32. When a transistor is wrongly biased, then

(a)  The emitter terminal gets heavily loaded
(b)  Excess production of heat is observed at the collector terminal
(c)  The output signal gets distorted
(d)  The AC load line gets distorted

Answer
Answer : (c)
Explanation
No answer description available for this question. Let us discuss.
33. Which of the following statements is/are correct ?

(a)  Hybrid parameter of transistors can be used only when input signal is large
(b)  Out of the four h parameters of transistor, hfe has the least numerical value
(c)  Statement A
(d)  Statement B

Answer
Answer : (d)
Explanation
No answer description available for this question. Let us discuss.
34. For a transistor, the current amplification factor :

(a)  α is greater than β
(b)  α is lesser than β
(c)  α is equal to β
(d)  α & β always equal to zero

Answer
Answer : (b)
Explanation
No answer description available for this question. Let us discuss.
35. The transistor must be operated in ……….. when employed as amplifying device.

(a)  Saturation region
(b)  Cut-off region
(c)  Active region
(d)  Any of the three regions

Answer
Answer : (c)
Explanation
No answer description available for this question. Let us discuss.
36. In a transistor, if IC = 100mA and IE = 100mA then the value of β is given by :

(a)  200
(b)  100
(c)  10
(d)  1

Answer
Answer : (a)
Explanation
No answer description available for this question. Let us discuss.
37. Strictly speaking, for an NPN transistor :

(a)  IC should be positive but IE should be negative
(b)  IC should be negative but IE should be positive
(c)  Both IC & IE should be positive
(d)  Both IC & IE should be negative

Answer
Answer : (a)
Explanation
No answer description available for this question. Let us discuss.
38. When a transistor is used as amplifier, then ………… breakdown is more destructive to the device.

(a)  Zener
(b)  Diode
(c)  Collector-Base
(d)  Base-Emitter

Answer
Answer : (d)
Explanation
No answer description available for this question. Let us discuss.
39. The variation of IC with VCE observed in a bipolar transistor output characteristic is called as :

(a)  Ohmic effect
(b)  Early effect
(c)  Late effect
(d)  Natural effect

Answer
Answer : (b)
Explanation
No answer description available for this question. Let us discuss.
40. Kirk effect in a transistor occurs when :

(a)  The majority carrier’s concentration in the collector becomes comparable to the donoratom doping density
(b)  The minority carrier’s concentration in the collector becomes comparable to the acceptor atom doping density
(c)  Emitter-base junction is reverse biased
(d)  The base region of transistor stretches into the collector region of transistor

Answer
Answer : (d)
Explanation
No answer description available for this question. Let us discuss.
41. The parasitic resistance value can be reduced by :

(a)  Operating the transistor in saturation region
(b)  Operating the transistor in cut-off region
(c)  Changing the transistor structure
(d)  Grounding the emitter terminal of the transistor

Answer
Answer : (c)
Explanation
No answer description available for this question. Let us discuss.
42. Which of the following is not a merit of transistors in place of vacuum tubes ?

(a)  Transistors are compact
(b)  Consume less power
(c)  Faster and economical
(d)  None of these

Answer
Answer : (d)
Explanation
No answer description available for this question. Let us discuss.
43. The most commonly used configuration of an n-p-n transistor as a switch is :

(a)  Common collector
(b)  Common emitter
(c)  Common base
(d)  Both common base and common collector

Answer
Answer : (c)
Explanation
No answer description available for this question. Let us discuss.
44. N-P-N transistors are preferred ones than P-N-P transistors for digital application because :

(a)  Electron mobility is more compared to holes mobility
(b)  They are cheaper
(c)  They are costlier
(d)  Easy availability in the market

Answer
Answer : (a)
Explanation
No answer description available for this question. Let us discuss.
45. A Schottky transistor used as a switch operates between :

(a)  Cut-off and saturation regions
(b)  Cut-off and active regions
(c)  Active and saturation regions
(d)  None of these

Answer
Answer : (b)
Explanation
No answer description available for this question. Let us discuss.
46. Which one of the following is a unique characteristic of Schottky transistor ?

(a)  Lower propagation delay
(b)  Higher propagation delay
(c)  Lower power dissipation
(d)  Higher power dissipation

Answer
Answer : (a)
Explanation
No answer description available for this question. Let us discuss.
47. Higher switching speed is possible in Schottky transistor than ordinary N-P-N transistor due to :

(a)  It operates in cut-off and saturation regions
(b)  It operates in active and saturation regions
(c)  It is prevented from going into saturation
(d)  It is prevented from going into cut-off

Answer
Answer : (c)
Explanation
No answer description available for this question. Let us discuss.
48. When a transistor is turned from ON to OFF, the transistor comes to OFF state :

(a)  Once the input signal is removed
(b)  As soon as the input signal is reversed
(c)  As soon as the power supply is switched off
(d)  After the excess charge stored in the base region is removed

Answer
Answer : (d)
Explanation
No answer description available for this question. Let us discuss.
49. The device having closer characteristics with an ideal current source is :

(a)  Vacuum diode
(b)  Zener diode
(c)  UJT
(d)  Transistor in common base mode

Answer
Answer : (d)
Explanation
No answer description available for this question. Let us discuss.
50. In the symbol of transistor the arrow mark shows :

(a)  Emitter
(b)  Collector
(c)  Base
(d)  Gate

Answer
Answer : (a)
Explanation
No answer description available for this question. Let us discuss.