1

### AIPMT 2010 Prelims

The device that can act as a complete electronic circuit is
A
junction diode
B
integrated circuit
C
junction transistor
D
zener diode

## Explanation

Integrated circuit can act as a complete electronic circuit.
2

### AIPMT 2010 Prelims

Which one of the following statement is false ?
A
Pure Si doped with trivalent impurities gives a p-type semiconductor.
B
Majority carries in a n-type semiconductor are holes.
C
Minority carries in a p-type semiconductor are electrons.
D
The resistance of intrinisic semiconductor decreases with increase of temperature.

## Explanation

In a n-type semiconductors, electrons are majority carriers and holes are minority carriers.
3

### AIPMT 2010 Prelims

To get an output Y = 1 in given circuit which of the following input will be correct ? A
A $\to$ 1,  B $\to$ 0,  C $\to$ 0
B
A $\to$ 1,  B $\to$ 0,  C $\to$ 1
C
A $\to$ 1,  B $\to$ 1,  C $\to$ 0
D
A $\to$ 0,  B $\to$ 1,  C $\to$ 0

## Explanation The Boolen expression for the given combination is

output Y = (A + B) · C

So it is clear that Y = 1, when A = 1, B = 0 and C = 1
4

### AIPMT 2009

Sodium has body centred packing. Distance between two nearest atoms is 3.7 $\mathop A\limits^ \circ$. The lattice parameter is
A
4.3 $\mathop A\limits^ \circ$
B
3.0 $\mathop A\limits^ \circ$
C
8.6 $\mathop A\limits^ \circ$
D
6.8 $\mathop A\limits^ \circ$

## Explanation

Distance between nearest atoms in body centred cubic lattice (bcc),

d = ${{\sqrt 3 } \over 2}a$

Given d = 3.7 $\mathop A\limits^ \circ$

$\therefore$ $a = {{3.7 \times 2} \over {\sqrt 3 }}$ = 4.3 $\mathop A\limits^ \circ$