24%20-%20Solids%20and%20Semi-conductor%20Devices

24%20-%20Solids%20and%20Semi-conductor%20Devices - 24 -...

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24 - SOLIDS AND SEMI-CONDUCTOR DEVICES Page 1 ( Answers at the end of all questions ) 1 ) In a common base amplifier, the phase difference between the input signal voltage and output voltage is ( a ) π ( b ) π / 4 ( c ) π / 2 ( d ) zero [ AIEEE 2005 ] 2 ) In a full wave rectifier, circuit operating from 50 Hz mains frequency, the fundamental frequency in the ripple would be ( a ) 25 Hz ( b ) 50 Hz ( c ) 70.7 Hz ( d ) 100 Hz [ AIEEE 2005 ] 3 ) When npn transistor is used as an amplifier ( a ) electrons move from base to collector ( b ) holes move from emitter to base ( c ) electrons move from collector to base ( d ) holes move from base to emitter [ AIEEE 2004 ] 4 ) For a transistor amplifier in common emitter configuration for load impedance of 1 K ( h fe = 50 and h oe = 25 µ A / V ), the current gain is ( a ) - 5.2 ( b ) - 15.7 ( c ) - 24.8 ( d ) - 48.78 [ AIEEE 2004 ] 5 ) A strip of copper and another of germanium are cooled from room temperature to 80 K. The resistance of ( a ) each of these increases ( b ) each of these decreases ( c ) copper strip increases and that of germanium decreases ( d ) copper strip decreases and that of germanium increases [ AIEEE 2004, 2003 ] 6 ) The menifestation of band structure in solids is due to ( a ) Heisenberg’s uncertainty principle ( b ) Pauli’s exclusion principle ( c ) Bohr’s correspondence principle ( d ) Boltzmann’s law [ AIEEE 2004 ] 7 ) When p - n junction diode is forward biased, then ( a ) the depletion region is reduced and barrier eight is increased ( b ) the depletion region is widened and barrier height is reduced ( c ) both the depletion region and barrier height
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This note was uploaded on 11/28/2011 for the course PHYSICS 300 taught by Professor Smith during the Spring '06 term at ITT Tech Flint.

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24%20-%20Solids%20and%20Semi-conductor%20Devices - 24 -...

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