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ECE Objective Questions { Semiconductor Physics and Diodes }

99. Avalanche breakdown diodes have
A. a positive temperature coefficient
B. a negative temperature coefficient
C. a breakdown voltage that is independent of temperature
D. none of these

100. Threshold energy level, which is the minimum amount of kinetic energy required before any impact collisions of free carriers to generate additional carriers by freeing them from their lattice structure, is (for silicon)
A. 2.25 eV
B. 1 eV
C. 10 eV
D. none of these

101. A zener is rated 20 V, 1 A. It was observed that a change in temperature equal to 100?C resulted in a change in breakdown voltage by 100 mV. Temperature coefficient in percentage is
A. 1% per ?C
B. 5 x 10-7% per ?C
C. indeterminate from given data
D. none of these

102. Which of the following is used as a passive component in electronic circuits?
A. Tunnel diode
B. Capacitor
C. Transistor
D. Vacuum diode

103.  The diameter of an atom is
A. 10-6 metre
B. 10-10 metre
C. 10-15 metre
D. 10-21 metre

104. The number of protons in an atom is called its
A. isotope number
B. atomic number
C. atomic weight
D. none of the above

105. Valence electrons are the
A. loosely packed electrons
B. mobile electrons
C. electrons present in the outermost orbit
D. electrons that do not carry and charge

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