BSNL TTA Electronics Devices And Circuits

BSNL TTA Electronics Devices And Circuits

NOTE-NO OF QUESTIONS-100(Basic)
ANSWER KEY-Correct answer is indicated by symbol (V) in options.
HINTS-In some questions options E-HINTS is indicating the hints of answer.
SAMPLE QUESTIONS AND ANSWER

1) A silicon diode measures a low value of resistance with the meter leads in both positions. The trouble, if any, is
A [ ]) the diode is open.
B [ ]) the diode is shorted to ground.
C [v]) the diode is internally shorted.
D [ ]) the diode is working correctly.

2) For a forward-biased diode, the barrier potential ________ as temperature increases.
A [v]) decreases
B [ ]) remains constant
C [ ]) increases
D []) None of above

3) The wide end arrow on a schematic indicates the ________ of a diode.
A [ ]) ground
B [ ]) direction of electron flow
C [ ]) cathode
D [v]) anode

BSNL TTA Electronics Devices And Circuits

4) An n-type semiconductor material
A [ ]) is intrinsic.
B [ ]) has trivalent impurity atoms added.
C [v]) has pentavalent impurity atoms added.
D [ ]) requires no doping.

5) For a forward-biased diode, as temperature is ________, the forward current ________ for a given value of forward voltage.
A [ ]) decreased, increases
B [v]) increased, increases
C [ ]) increased, decreases
D [ ]) decreased, decreases

6) Which statement best describes an insulator?
A [ ]) A material with many free electrons.
B [ ]) A material doped to have some free electrons.
C [v]) A material with few free electrons.
D [ ]) none of these

7) An ideal diode presents a(n) ________ when reversed-biased and a(n) ________ when forward-biased.
A [v]) open, short
B [ ]) short, open
C [ ]) open, open
D [ ]) short, short

BSNL TTA Electronics Devices And Circuits

8) A reverse-biased diode has the ________ connected to the positive side of the source, and the ________ connected to the negative side of the source.
A [v]) cathode, anode
B [ ]) cathode, base
C [ ]) base, anode
D [ ]) anode, cathode

9) What types of impurity atoms are added to increase the number of conduction-band electrons in intrinsic silicon?
A [ ]) bivalent
B [v]) pentavalent
C [ ]) trivalent
D [ ]) none of these

10) What factor(s) do(es) the barrier potential of a pn junction depend on?
A [ ]) type of semiconductive material
B [ ]) the amount of doping
C [ ]) the temperature
D [v]) all of the above

11) Reverse breakdown is a condition in which a diode
A [v]) is subjected to a large reverse voltage
B [ ]) is reverse-biased and there is a small leakage current.
C [ ]) has no current flowing at all.
D [ ]) is heated up by large amounts of current in the forward direction.

12) There is a small amount of current across the barrier of a reverse-biased diode. This current is called
A [ ]) forward-bias current.
B [ ]) reverse breakdown current.
C [ ]) conventional current.
D [v]) reverse leakage current

BSNL TTA Electronics Devices And Circuits

13) As the forward current through a silicon diode increases, the voltage across the diode
A [ ]) increases to a 0.7 V maximum.
B [ ]) decreases.
C [v]) is relatively constant.
D [ ]) decreases and then increases.

14) Doping of a semiconductor material means
A [ ]) Doping of a semiconductor material means
B [ ]) that impurities are added to increase the resistance of the material.
C [v]) that impurities are added to decrease the resistance of the material
D [ ]) that all impurities are removed to get pure silicon.

15) The forward voltage across a conducting silicon diode is about
A [ ]) 0.3 V.
B [ ]) 1.7 V.
C [ ]) -0.7 V.
D [v]) 0.7 V.

BSNL TTA Electronics Devices And Circuits

16) The most common type of diode failure is a(n) ________.
A [v]) open
B [ ]) short
C [ ]) resistive
D [ ]) all of these

17) What occurs when a conduction-band electron loses energy and falls back into a hole in the valence band?
A [ ]) doping
B [v]) recombination
C [ ]) generation
D [ ]) diffusion

18) A silicon diode is forward-biased. You measure the voltage to ground from the anode at ________, and the voltage from the cathode to ground at ________.
A [ ]) 0 V, 0.3 V
B [v]) 2.3 V, 1.6 V
C [ ]) 1.6 V, 2.3 V
D [ ]) 0.3 V, 0 V

BSNL TTA Electronics Devices And Circuits

19) The term bias in electronics usually means
A [ ]) the value of ac voltage in the signal.
B [ ]) the condition of current through a pn junction
C [v]) the value of dc voltages for the device to operate properly.
D [ ]) the status of the diode.

20) Which capacitance dominates in the reverse-bias region?
A [v]) depletion
B [ ]) conversion
C [ ]) Diffusion
D [ ]) None of the above

BSNL TTA Electronics Devices And Circuits