Special Diodes – Exercise – 1

1. A Zener diode :

(a)  Is a battery under forward biased condition
(b)  Acts like battery when it breakdowns
(c)  Is a switch
(d)  Is a device having barrier potential more than 5V

Answer
Answer : (b)
Explanation
No answer description available for this question. Let us discuss.
2. At 25ºC, a Zener diode rates at 2 watts, its power rating at 50ºC will be :

(a)  Zero watts
(b)  Less than 1 watt
(c)  Greater than 2 watts
(d)  Less than 2 watts

Answer
Answer : (d)
Explanation
No answer description available for this question. Let us discuss.
3. Silicon is appreciably employed as a base material compared to germanium while manufacturing Zener diode since :

(a)  silicon is abundantly available
(b)  it is costlier
(c)  it has low current capability
(d)  it has high temperature capability

Answer
Answer : (d)
Explanation
No answer description available for this question. Let us discuss.
4. The capacitance of a varactor diode increases, when the reverse voltage across it is :

(a)  Decreased
(b)  Increased
(c)  Kept constant
(d)  None of the above

Answer
Answer : (a)
Explanation
No answer description available for this question. Let us discuss.
5. The main advantage of a point contact diode is that :

(a)  The ratio of forward current to reverse current is very high
(b)  Low input impedance
(c)  Its cut-in voltage is equal to zero
(d)  Its reverse resistance is infinite

Answer
Answer : (a)
Explanation
No answer description available for this question. Let us discuss.
6. Which one of the following is a Square law device ?

(a)  Zener diode
(b)  Crystal diode
(c)  Tunnel diode
(d)  Varactor diode

Answer
Answer : (d)
Explanation
No answer description available for this question. Let us discuss.
7. Match the given lists.
List I                                            List II
(Name of the device)                   (Application)
A. Diode                                      1. Rectification
B. Tunnel diode                         2. Microwave switching
C. Zener diode                           3. As oscillator
D. PIN diode                              4. Voltage stabilization

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

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.
9. Tunnel diode is :

(a)  Linear resistor
(b)  Current dependent resistor
(c)  Voltage dependent resistor
(d)  Non-linear resistor

Answer
Answer : (c)
Explanation
No answer description available for this question. Let us discuss.
10. One of the following microwave diodes is suitable for very low power oscillators :

(a)  Tunnel diode
(b)  Gunn diode
(c)  PIN diode
(d)  Zener diode

Answer
Answer : (a)
Explanation
No answer description available for this question. Let us discuss.
11. For fastest switching operation, it is preferable to use :

(a)  P-N junction diode
(b)  Vacuum diode
(c)  Zener diode
(d)  Schottky diode

Answer
Answer : (d)
Explanation
No answer description available for this question. Let us discuss.
12. Which of the following devices is suitable for very low power oscillator circuit only ?

(a)  TRAPATT diode
(b)  IMPATT diode
(c)  Gunn diode
(d)  Tunnel diode

Answer
Answer : (d)
Explanation
No answer description available for this question. Let us discuss.
13. The transferred-electron bulk effect occurs in :

(a)  Germanium
(b)  Gallium arsenide
(c)  Silicon
(d)  Metal-semiconductor junction

Answer
Answer : (b)
Explanation
No answer description available for this question. Let us discuss.
14. Schottky transistors are preferred over normal transistors in digital applications because of their :

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

Answer
Answer : (c)
Explanation
No answer description available for this question. Let us discuss.
15. When used as switch, a Schottky transistor switches between :

(a)  Cut-off and active regions
(b)  Cut-off and saturation regions
(c)  Active and saturation regions
(d)  Different operation points in the active region

Answer
Answer : (a)
Explanation
No answer description available for this question. Let us discuss.
16. The devices commonly used for making digital circuits are :

(a)  Mechanical switches
(b)  Relays
(c)  Vacuum tubes
(d)  Semiconductor devices

Answer
Answer : (d)
Explanation
No answer description available for this question. Let us discuss.
17. Which one of the following possesses negative resistance characteristics ?

(a)  Schottky diode
(b)  Tunnel diode
(c)  PN junction diode
(d)  Hot-carrier diode

Answer
Answer : (b)
Explanation
No answer description available for this question. Let us discuss.
18. The region between the peak and valley points of the tunnel diode is called as :

(a)  Pinch-off region
(b)  Saturation region
(c)  Cut-off region
(d)  Negative conduction region

Answer
Answer : (d)
Explanation
No answer description available for this question. Let us discuss.
19. Avalanche breakdown occurs when :

(a)  The forward current is excessive
(b)  The forward bias exceeds a certain value
(c)  The reverse bias exceeds a certain value
(d)  The potential barrier is reduced to zero

Answer
Answer : (c)
Explanation
No answer description available for this question. Let us discuss.
20. Zener diode exhibits :

(a)  Avalanche breakdown
(b)  Zener breakdown
(c)  Both (a) & (b)
(d)  Neither (a) nor (b)

Answer
Answer : (c)
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.
22. Match the following
P. SCR                              (I) Low current SCR without gate
Q. Triac                           (II) Low current SCR with gate
R. Schottky diode         (III) Uni-directional
S. SCS                             (IV) Bi-directional

(a)  P – IV, Q – III, R – I, S – II
(b)  P – I, Q – II, R – III, S – IV
(c)  P – III, Q – IV, R – I, S – II
(d)  P -I, Q – IV, R – II, S – III

Answer
Answer : (c)
Explanation
No answer description available for this question. Let us discuss.
23. In a Zener diode :

(a)  P & N regions are lightly doped
(b)  The depletion region is wide
(c)  P & N regions are heavily doped
(d)  The junction field current is small

Answer
Answer : (c)
Explanation
No answer description available for this question. Let us discuss.
24. In tunnel diode, the impurity concentration is in the order of :

(a)  1 part in 10^10 parts
(b)  1 part in 10^6 parts
(c)  1 part in 10^9 parts
(d)  1 part in 10^3 parts

Answer
Answer : (d)
Explanation
No answer description available for this question. Let us discuss.
25. Which diode is otherwise known as ESAKI diode ?

(a)  PIN diode
(b)  Schottky barrier diode
(c)  GUNN diode
(d)  Tunnel diode

Answer
Answer : (d)
Explanation
No answer description available for this question. Let us discuss.
26. The barrier potential of Schottky diode is :

(a)  0.25 V
(b)  0.35 V
(c)  0.45 V
(d)  0.56 V

Answer
Answer : (a)
Explanation
No answer description available for this question. Let us discuss.
27. Across a varactor diode, an increase in its reverse bias potential causes :

(a)  Width of depletion layer to increase thus increasing the capacitance
(b)  Width of depletion layer to decrease thus increasing the capacitance
(c)  Width of depletion layer to increase thus decreasing the capacitance
(d)  Width of depletion layer to decrease thus decreasing the capacitance

Answer
Answer : (c)
Explanation
No answer description available for this question. Let us discuss.
28. Which among the following diodes has zero breakdown voltage ?

(a)  Zener diode
(b)  Schottky diode
(c)  Backward diode
(d)  Tunnel diode

Answer
Answer : (d)
Explanation
No answer description available for this question. Let us discuss.
29. A Zener diode may be thought as open for :

(a)  0V < V < VZ
(b)  0V > V > VZ
(c)  0V > V < VZ
(d)  0V < V > VZ

Answer
Answer : (a)
Explanation
No answer description available for this question. Let us discuss.
30. A Schottky diode has :

(a)  Insulator – Semiconductor junction
(b)  Semiconductor – Semiconductor junction
(c)  Metal – Semiconductor junction
(d)  Metal – Metal junction

Answer
Answer : (c)
Explanation
No answer description available for this question. Let us discuss.
31. Which diode is otherwise called as hot carrier diode ?

(a)  Schottky diode
(b)  Tunnel diode
(c)  PIN diode
(d)  Varactor diode

Answer
Answer : (a)
Explanation
No answer description available for this question. Let us discuss.
32. The dynamic impedance of Zener diode ………. with increase in the current flow through it.

(a)  Increases
(b)  Decreases
(c)  Remains unaffected
(d)  Is independent

Answer
Answer : (b)
Explanation
No answer description available for this question. Let us discuss.
33. The following statement forms the basis of one of the following electronic devices. Identify it. “If a particle is electronic on a potential barrier with energy certainly less than the height of the potential barrier, it will not necessarily be reflected by the barrier but there is always a probability that it may cross the barrier and continue its forward motion”.

(a)  Tunnel diode
(b)  PIN diode
(c)  Schottky diode
(d)  Metal oxide semiconductor diode

Answer
Answer : (a)
Explanation
No answer description available for this question. Let us discuss.
34. Identify the false statement with respect to the Zener diode.

(a)  Zener diode is needed for voltage regulation
(b)  Zener diode is operated in reverse biased condition
(c)  Zener diode has similar characteristics to that of an ideal current source
(d)  None of the above

Answer
Answer : (c)
Explanation
No answer description available for this question. Let us discuss.
35. Match the items in Group I with items in Group II most suitably
Group I                                                 Group II
(P) LED                                            (1) Heavily doped
(Q) Avalanche photo diode          (2) Coherent radiation
(R) Tunnel diode                            (3) Spontaneous emission
(S) LASER                                       (4) Current gain

(a)  P-2, Q-1, R-3, S-4
(b)  P-4, Q-3, R-2, S-1
(c)  P-3, Q-4, R-1, S-2
(d)  P-3, Q-2, R-1, S-4

Answer
Answer : (c)
Explanation
No answer description available for this question. Let us discuss.
36. ……… is another type of VVC diode.

(a)  PN junction diode
(b)  Step recovery diode
(c)  PIN diode
(d)  Schottky diode

Answer
Answer : (b)
Explanation
No answer description available for this question. Let us discuss.
37. Tunneling phenomena was invented by :

(a)  Einstein
(b)  Henry Hill
(c)  Dr. Fresnel
(d)  Dr. Leo Easaki

Answer
Answer : (d)
Explanation
No answer description available for this question. Let us discuss.
38. The switching speed of a Schottky diode is :

(a)  Lower than p-n junction diode
(b)  Same as p-n junction diode
(c)  Higher than p-n junction diode
(d)  Can’t define

Answer
Answer : (c)
Explanation
No answer description available for this question. Let us discuss.
39. The Schottky diode is :

(a)  A vacuum device
(b)  A metal – semiconductor device
(c)  Purely semiconductor device
(d)  MOS device

Answer
Answer : (b)
Explanation
No answer description available for this question. Let us discuss.
40. The device having scalar characteristics with that of an ideal voltage source is :

(a)  FET
(b)  P-N-P transistor
(c)  Zener diode
(d)  MOSFET

Answer
Answer : (c)
Explanation
No answer description available for this question. Let us discuss.
41. The temperature coefficient of a Zener diode changes from negative to positive :

(a)  Below 5 V
(b)  Above 6 V
(c)  Between 5 V and 6 V
(d)  Exactly at 0 V

Answer
Answer : (c)
Explanation
No answer description available for this question. Let us discuss.
42. A back diode :

(a)  Is ordinary Zener diode
(b)  Is used to rectify strong signals
(c)  Conducts better in the forward than in the reverse directions
(d)  Is used to rectify weak signals whose peak amplitudes are between 0.1 V and 0.7 V

Answer
Answer : (d)
Explanation
No answer description available for this question. Let us discuss.
43. ……….. utilizes the cumulative multiplication principle of carriers through field induced impact ionization.

(a)  Zener diode
(b)  Varactor diode
(c)  PIN diode
(d)  Avalanche diode

Answer
Answer : (d)
Explanation
No answer description available for this question. Let us discuss.
44. The major application of tunnel diode is :

(a)  As voltage controllable device
(b)  As switching device in digital circuits
(c)  As oscillator
(d)  As rectifier

Answer
Answer : (b)
Explanation
No answer description available for this question. Let us discuss.
45. In Schottky barrier diode, conduction is :

(a)  Entirely by electrons
(b)  Entirely by holes
(c)  Mainly by electrons and partially by holes
(d)  Mainly by holes and partially by electrons

Answer
Answer : (a)
Explanation
No answer description available for this question. Let us discuss.
46. Tunnel diode is basically a junction diode with :

(a)  High doping in p region alone
(b)  High doping in n region alone
(c)  High doping in both p and n regions
(d)  Low doping in both p and n regions

Answer
Answer : (c)
Explanation
No answer description available for this question. Let us discuss.
47. In a tunnel diode, depletion layer width is of the order :

(a)  100 Angstroms
(b)  0.1 Micron
(c)  1 Micron
(d)  5 Microns

Answer
Answer : (c)
Explanation
No answer description available for this question. Let us discuss.
48. On increasing the current through the Zener diode by a factor of 2, the voltage across the diode :

(a)  Gets doubled
(b)  Becomes 4 times
(c)  Becomes half
(d)  Remains the same

Answer
Answer : (d)
Explanation
No answer description available for this question. Let us discuss.
49. The dynamic resistance of a Zener diode :

(a)  Increases with increase in current
(b)  Decreases with increase in current
(c)  Decreases with decrease in current
(d)  Is independent of variation in current

Answer
Answer : (b)
Explanation
No answer description available for this question. Let us discuss.
50. A voltage regulator is based on the principle of :

(a)  Rectification
(b)  Amplification
(c)  Zener breakdown
(d)  Avalanche breakdown

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