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Electrical Engineering Objective Questions { Material And Components }



85. Hole in a lattice is defined as
A. free proton
B. free neutron
C. vacancy created by removal of electron from covalent band
D. acceptor ion

86. In a pure semiconductor, electric current is due to
A. holes alone
B. electrons alone
C. both holes and electrons
D. valence electrons alone

87. Forbidden energy gap between valence band and conduction band is least in the case of
A. mica
B. pure silicon
C. pure germanium
D. impure silicon

88.  Temperature coefficient of resistance in a pure semiconductor is
A. zero
B. positive
C. negative
D. dependent on size of specimen

89. Donor impurity atom in a semiconductor result in new
A. wide energy band
B. narrow energy band
C. discrete energy level just below conduction level
D. discrete energy level just above valence level

90. Acceptor impurity atoms in a semiconductor result in new
A. wide energy band
B. narrow energy band
C. discrete energy level just below conduction level
D. discrete energy level just above valence level

91. In Ge or si, medium doping corresponds to impurity of the following order
A. 1 part in 108
B. 1 part in 106
C. 1 part in 105
D. 1 part in 104

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