Symbolic representation of four logic gates are shown as
Pick out which ones are for AND, NAND and NOT gates, respectively
A
(ii), (iii) and (iv)
B
(iii), (ii) and (i)
C
(iii), (ii) and (iv)
D
(ii), (iv) and (iii)
Explanation
AND, NAND and NOT gates are (ii), (iv) and (iii) respectively.
2
AIPMT 2011 Prelims
MCQ (Single Correct Answer)
A transistor is operated in common emitter configuration at VC = 2 V such that a change in the base current from 100 $$\mu $$A to 300 $$\mu $$A produces a change in the collector current from 10 mA to 20 mA. The current gain is
A
50
B
75
C
100
D
25
Explanation
Current gain, $$\beta $$ = $${{\Delta {I_C}} \over {\Delta {I_B}}}$$
A Zener diode, having breakdown voltage equal to 15 V, is used in a voltage regulator circuit shown in figure. The current through the diode is
A
5 mA
B
10 mA
C
15 mA
D
20 mA
Explanation
Voltage across 250 Ω resistance
= 20 V – 15 V = 5 V
Now current through 250 $$\Omega $$ resistance:
5/250 = 20 mA
If voltage across load resistance 1 k$$\Omega $$ is 15 V, then
current through 1 kΩ is 15/1000 = 15 mA
The current through the zener diode is
= Current through 250 $$\Omega $$ resistance
– Current through 1 k$$\Omega $$ resistance.
= 20 - 15
= 5 mA
4
AIPMT 2011 Prelims
MCQ (Single Correct Answer)
If a small amount of antimony is added to germanium crystal
A
it becomes a p-type semiconductor
B
the antimony becomes an acceptor atom
C
there will be more free electrons than holes in the semiconductor
D
its resistance is increased
Explanation
If a small amount of antimony is added to
germanium crystal, crystal becomes n-type semiconductor. Hence, there will be more free electrons
than holes.
Questions Asked from Semiconductor Electronics
On those following papers in MCQ (Single Correct Answer)
Number in Brackets after Paper Indicates No. of Questions