1

AIPMT 2010 Prelims

A common emitter amplifier has a voltage gain of 50, an input impedance of 100 $\Omega$ and an output impedance of 200 $\Omega$. The power gain of the amplifier is
A
500
B
1000
C
1250
D
50

Explanation

Voltage gain= $\beta$ × Impedance gain

$\Rightarrow$50 = β × (200/100)

$\Rightarrow$ $\beta$ = 25

Power gain = $\beta$ × Voltage gain

= 25 × 50 = 1250
2

AIPMT 2010 Prelims

Which one of the following bonds produces a solid that reflects light in the visible region and whose electrical conductivity decreases with temperature and has high melting point ?
A
metallic bonding
B
van der Waal's bonding
C
ionic bonding
D
covalent bonding

Explanation

In case of metal, conductivity decreases with increase in temperature and metal has high melting point.
3

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.
4

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.