Copper has face centered cubic (fcc) lattice with interatomic spacing equal to 2.54 $$\mathop A\limits^ \circ $$. The value of lattice constant for this lattice is
Carbon, silicon and germanium atoms have four valence electrons each. Their valence and conduction bands are separated by energy band gaps represented by (Eg)C, (Eg)si and (Eg)Ge respectively. Which one of the following relationships is true in their case?
A
(Eg)C > (Eg)Si
B
(Eg)C < (Eg)Si
C
(Eg)C = (Eg)Si
D
(Eg)C < (Eg)Ge.
Explanation
Band gap of carbon is 5.5 eV while that of
silicon is 1.1 eV
$$ \therefore $$ (Eg)C $$>$$ (Eg)Si
3
MCQ (Single Correct Answer)
AIPMT 2005
Zener diode is used for
A
amplification
B
rectification
C
stabilisation
D
producing oscillations in an oscillator.
Explanation
Zener diode is used for stabilisation while
p-n junction diode is used for rectification.
4
MCQ (Single Correct Answer)
AIPMT 2005
Application of a forward bias to a p-n junction
A
widens the depletion zone
B
increases the potential difference across the depletion zone
C
increases the number of donors on the n side
D
decreases the electric field in the depletion zone.
Explanation
Number of donors is more because electrons
from –ve terminal of the cell pushes (enters)
the n side and decreases the number of
uncompensated pentavalent ion due to which
potential barrier is reduced. The neutralised
pentavalent atom are again in position to
donate electrons.
Questions Asked from Semiconductor Electronics
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