The figure shows a logic circuit with two inputs A and B and the output C. The voltage wave forms across A, B and C are as given. The logic circuit gate is
A
OR gate
B
NOR gate
C
AND gate
D
NAND gate
2
AIPMT 2012 Prelims
MCQ (Single Correct Answer)
+4
-1
C and Si both have same lattice structure; having 4 bonding electrons in each. However, C is insulator where as Si is intrinsic semiconductor. This is because
A
In case of C the valence band is not completely filled at absolute zero temperature.
B
In case of C the conduction band is partly filled even at absolute zero temperature.
C
The four bonding electrons in the case of C lie in the second orbit, whereas in the case of Si they lie in the third.
D
The four bonding electrons in the case of C lie in the third orbit , whereas for Si they lie in the fourth orbit.
3
AIPMT 2011 Mains
MCQ (Single Correct Answer)
+4
-1
Pure Si at 500 K has equal number of electron (ne) and hole (nh) concentrations of 1.5 $$ \times $$ 1016 m$$-$$3. Doping by indium increases nh to 4.5 $$ \times $$ 1022 m$$-$$3. The doped semiconductor is of
A
p-type having electron concentration ne = 5 $$ \times $$ 109 m$$-$$3
B
n-type with electron concentration ne = 5 $$ \times $$ 1022 m$$-$$3
C
p-type with electron concentration ne = 2.5 $$ \times $$ 1010 m$$-$$3
D
n-type with electron concentration ne = 2.5 $$ \times $$ 1023 m$$-$$3
4
AIPMT 2011 Mains
MCQ (Single Correct Answer)
+4
-1
In the following figure, the diodes which are forward biased, are
