NEET Questions - Physics - Semiconductor Electronics

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Question bank:

In a common emitter transistor amplifier, the audio signal voltage across resistance of 1 k $Ω$ is 2V. If the base resistance is 200 $Ω$ and the current amplification factor is 50, the input signal voltage will be

4 mV
8 mV
16 mV
32 mV

If a small amount of aluminium is added to the silicon crystal

Its resistance is decreased
It becomes a p-type semiconductor
There will be less free-electron than holes in semiconductor
All of these are correct

A transistor is operated in common emitter configuration at $V_{c} = 10 V .$ When base current is changed from 10mA to 30mA, it produces a change in emitter current from 2A to 4A, the current amplification factor is

100
99
10
9

When a p-n junction is forward biased:

Depletion region becomes thick
p-side is at a higher potential than n side
Current flowing is zero
Effective resistance is of the order of

10^{6} W

When a transistor is used as a switch it is in:

Active state
Cut off state
Saturation state
Both cut off state and saturation state are possible

Use of transistor as an amplifier works in the region -

Cut off region
Saturation region
Passive region
Active region

Which of the following is correct for n-type semiconductor?

Electron is majority carriers and trivalent atoms are dopants.
Electrons are majority carriers and pentavalent atoms are dopants.
Holes are majority carriers and pentavalent atoms are dopants.
Holes are majority carriers and trivalent atoms are dopants.

$If α be the current gain of a transistor in common base mode and β be the current gain in common emitter mode then -$

α < 1

β > 1

α = \frac{β}{1 + β}

All of these

For a transistor amplifier, the power gain and voltage gain are 150 and 10 respectively. The current gain is-

\frac{1}{10}

\frac{1}{15}

15
1500

In semiconductors, which of the following gives the law of mass action (where symbols have their usual meanings)-

n_{1} = n_{e} = n_{h}

{n_{i}}^{2} = n_{e} n_{h}

n_{h} > > n_{e}

n_{h} < < n_{e}

The conductivity of an n-type semiconductor whose density of conduction electrons is $n_{e}$ , Density of holes is $n_{h}$ , Mobility of conduction electrons is m and Mobility of holes is $m_{h},$ will be

e [n_{e} m_{h} + n_{e} m_{e}]

e [n_{e} m_{e} + n_{h} m_{e}]

{en}_{e} [m_{e} + m_{h}]

e [n_{e} m_{e} + n_{h} m_{h}]

A transistor is used in common emitter mode in an amplifier circuit. When a signal of 10 mV is added to the base-emitter voltage, the base current changes by 15 $μ$ A and the collector current changes by 1.5 mA. The current gain b will be

50
48
100
200

In a common-emitter transistor, the phase difference between input and output is:

Zero

π

π

π

$A semiconductor is known to have an electron concentration of 8 x 10^{13} {cm}^{- 3} and hole concentration of 5 x 10^{12} {cm}^{- 3} . The semiconductor is$

N-type
P-type
intrinsic
insulator

In a common emitter transistor amplifier, the audio signal vlotage across the collector is 3V. The resistance of collector is 3k $Ω$ . If current gain is 100 and the base resistance is 2k $Ω$ , the voltage and power gain of the amplifier is

200 and 1000
15 and 200
150 and 15000
20 and 2000

NEET Physics Questions: Semiconductor Electronics

Question bank:

In a common emitter transistor amplifier, the audio signal voltage across resistance of 1 kΩ is 2V. If the base resistance is 200Ω and the current amplification factor is 50, the input signal voltage will be