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ECE Objective Questions { Semiconductor Physics and Diodes }



85. Mark the incorrect statement (with reference to zener diode)
A. A 6.2 V zener diode shall operate from voltages equal to or more than 6.2 V
B. While doing an experiment with zener diode as voltage regulator, it was observed that due to certain change in input voltage, the current through the circuit increased by a factor of 10 whereas voltage across the output terminals changed by a factor of 1-2 only.
C. Zener diode principle is different from that avalanche diode
D. A zener diode with a breakdown voltage of 6.2 V shall get destroyed if a voltage greater than the rated value incidently appears across the diode terminals with cathode positive and anode negative

86. The important specifications of a zener diode are
A. its breakdown voltage and power dissipation
B. breakdown voltage, dynamic impedance and power dissipation
C. breakdown voltage and dynamic impedance
D. none of these

87.  A tunnel diode is an ordinary P?N junction diode with
A. higher impurity concentration in N?region
B. higher impurity concentration in P?region
C. higher impurity concentration in P and N regions
D. lower impurity concertration in P and N regions

88. A typical value of impurity concentration in a tunnel diode is
A. 1 part in 108 parts
B. 1 part in 106 parts
C. 1 part in 103 parts
D. none of these

89. A higher impurity concentration
A. decreases the depletion width of the semiconductor junction
B. increases the depletion width of the semiconductor junction
C. does not have any effect on depletion width
D. none of these

90. Tunnel diodes are fabricated from
A. germanium
B. silicon
C. either germanium or gallium arsenide
D. gallium arsenide

91. Tunnel diode characteristic differ from ordinary junction diode characteristics in the respect that former's
A. are liner
B. non-linear
C. exhibit a negative resistance region
D. none of these

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