1
AIPMT 2012 Prelims
MCQ (Single Correct Answer)
+4
-1
Electron in hydrogen atom first jumps from third excited state to second excited state and then from second excited to the first excited state. The ratio of the wavelengths $$\lambda $$1 : $$\lambda $$2 emitted in the two cases is
A
$${7 \over 5}$$
B
$${27 \over 20}$$
C
$${27 \over 5}$$
D
$${20 \over 7}$$
2
AIPMT 2012 Prelims
MCQ (Single Correct Answer)
+4
-1
Two ideal diodes are connected to a battery as shown in the circuit. The current supplied by the battery is

AIPMT 2012 Prelims Physics - Semiconductor Electronics Question 90 English
A
0.75 A
B
zero
C
0.25 A
D
0.5 A
3
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.
4
AIPMT 2012 Prelims
MCQ (Single Correct Answer)
+4
-1
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
AIPMT 2012 Prelims Physics - Semiconductor Electronics Question 86 English
A
OR gate
B
NOR gate
C
AND gate
D
NAND gate
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