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

$\mathrm{If} \mathrm{\alpha } \mathrm{be} \mathrm{the} \mathrm{current} \mathrm{gain} \mathrm{of} \mathrm{a} \mathrm{transistor} \mathrm{in} \mathrm{common} \mathrm{base} \mathrm{mode} \mathrm{and} \mathrm{\beta } \mathrm{be} \mathrm{the} \mathrm{current} \mathrm{gain} \mathrm{in}$
$\mathrm{common} \mathrm{emitter} \mathrm{mode} \mathrm{then}-$

1.  $\mathrm{\alpha } < 1$

2.  $\mathrm{\beta } > 1$

3.  $\mathrm{\alpha } = \frac{\mathrm{\beta }}{1 + \mathrm{\beta }}$

4.  All of these

The input resistance of a silicon transistor is

100 $\mathrm{\Omega }$. Base current is changed by 40 $\mathrm{\mu A}$

which results in a change in collector current

by 2 mA. This transistor is used as a common-

emitter amplifier with a load resistance of 4 k$\mathrm{\Omega }$.

The voltage gain of the amplifier is

1. 2000

2. 3000

3. 4000

4. 1000

The device that can act as a complete electronic circuit is

1. Junction diode

2. Integrated circuit

3. Junction transistor

4. Zener diode

For transistor action:

Which of the following pairs of statements is correct?
1. (d) and (a)
2. (a) and (b)
3. (b) and (c)                                       
4. (c) and (d)

A transistor is operated in common-emitter configuration at $V_c=2volt$ such that a change in the base current from 100 $\mu A$ to 200 $\mu A$ produces a change in the collector current from 5 mA to 10 mA. The current gain is 

1. 75                                2. 100

3. 150                              4. 50

The emitter-base junction of a transistor is …… biased while the collector-base junction is ……. biased.
1. reverse, forward                       

2. reverse, reverse

3. forward, forward                       

4. forward, reverse

In an NPN transistor the collector current is 24 mA. If 80% of electrons reach collector its base current in mA is

1. 36                       2. 26
3. 16                       4. 6

If $\mathrm{\alpha }$ = 0.98 and current through emitter ${\mathrm{i}}_{\mathrm{e}}$ = 20 mA, the value of $\mathrm{\beta }$ is 
(a) 4.9                  (b) 49
(c) 96                   (d) 9.6

 If ${\mathrm{l}}_1$, ${\mathrm{l}}_2$, ${\mathrm{l}}_3$ are the lengths of the emitter, base and collector of a transistor then 
(1)${\mathrm{l}}_1$= ${\mathrm{l}}_2$ = ${\mathrm{l}}_3$                   

(2) ${\mathrm{l}}_3$ <${\mathrm{l}}_2$> ${\mathrm{l}}_1$

(3) ${\mathrm{l}}_3$<  ${\mathrm{l}}_1$ < ${\mathrm{l}}_2$                 

(4) ${\mathrm{l}}_3$> ${\mathrm{l}}_1$>${\mathrm{l}}_2$