# In a common emitter transistor amplifier, the audio signal voltage across resistance of 1 k$\Omega$ is 2V. If the base resistance is 200$\Omega$ and the current amplification factor is 50, the input signal voltage will be (1) 4 mV (2) 8 mV (3) 16 mV (4) 32 mV

Subtopic:  Transistor (OLD NCERT) |
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If a small amount of aluminium is added to the silicon crystal:

 1 its resistance decreases. 2 it becomes a p-type semiconductor. 3 there will be fewer free electrons than holes in the semiconductor. 4 All of these are correct.
Subtopic:  Types of Semiconductors |
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A transistor is operated in common emitter configuration at  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

1.  100

2.  99

3.  10

4.  9

Subtopic:  Applications of Transistor (OLD NCERT) |
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When a $$\mathrm{p\text-n}$$ junction is forward biased, then:
 1 the depletion region becomes thick. 2 the $$\mathrm{p}\text-$$side is at a higher potential than $$\mathrm{n\text-}$$side. 3 the current flowing is zero. 4 the effective resistance is of the order of $$10^6 ~\Omega$$.
Subtopic:  PN junction |
82%
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When a transistor is used as a switch it is in:

1.  Active state

2.  Cut off state

3.  Saturation state

4.  Both cut off state and saturation state are possible

Subtopic:  Applications of Transistor (OLD NCERT) |
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Which of the following is correct for $$\mathrm{n}$$-type semiconductors?

 1 electron is the majority carriers and trivalent atoms are dopants. 2 electrons are majority carriers and pentavalent atoms are dopants. 3 holes are majority carriers and pentavalent atoms are dopants. 4 holes are majority carriers and trivalent atoms are dopants.
Subtopic:  Types of Semiconductors |
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1.

2.

3.

4.  All of these

Subtopic:  Transistor (OLD NCERT) |
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In semiconductors, which of the following gives the law of mass action?
(where symbols have their usual meanings.)
1. $$n_i=n_e=n_h$$
2. $$n_i^2=n_en_h$$
3. $$n_h>> n_e$$
4. $$n_h<<n_e$$

Subtopic:  Types of Semiconductors |
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The conductivity of an n-type semiconductor whose density of conduction electrons is ${\mathrm{n}}_{\mathrm{e}}$, Density of holes is ${\mathrm{n}}_{\mathrm{h}}$, Mobility of conduction electrons is ${\mathrm{m}}_{\mathrm{e}}$and Mobility of holes is ${\mathrm{m}}_{\mathrm{h}},$ will be

1.

2.

3.

4.

Subtopic:  Types of Semiconductors |
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The current through an ideal p-n junction diode shown in the circuit will be -

1.  5 A

2.  0.2 A

3.  0.6 A

4.  Zero

Subtopic:  PN junction |
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