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

1.  $\mathrm{\alpha } < 1$

2.  $\mathrm{\beta } > 1$

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

4.  All of these

 

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. \(n_h<<n_e\)

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.  $\mathrm{e}\left[{\mathrm{n}}_{\mathrm{e}}{\mathrm{m}}_{\mathrm{h}} + {\mathrm{n}}_{\mathrm{e}}{\mathrm{m}}_{\mathrm{e}}\right]$

2.  $\mathrm{e}\left[{\mathrm{n}}_{\mathrm{e}}{\mathrm{m}}_{\mathrm{e}} + {\mathrm{n}}_{\mathrm{h}}{\mathrm{m}}_{\mathrm{e}}\right]$

3.  ${\mathrm{en}}_{\mathrm{e}}\left[{\mathrm{m}}_{\mathrm{e}} + {\mathrm{m}}_{\mathrm{h}}\right]$

4.  $\mathrm{e}\left[{\mathrm{n}}_{\mathrm{e}}{\mathrm{m}}_{\mathrm{e}} + {\mathrm{n}}_{\mathrm{h}}{\mathrm{m}}_{\mathrm{h}}\right]$

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

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

1.  Zero

2.  $\mathrm{\pi }$/2

3.  $\mathrm{\pi }$/3

4.  $\mathrm{\pi }$

$\mathrm{In} \mathrm{the} \mathrm{given} \mathrm{circuit} \mathrm{power}$
$\mathrm{developed} \mathrm{in} 1\mathrm{k\Omega } \mathrm{resistor} \mathrm{is}$

1.  36 mW

2.  12 mW

3.  144 mW

4.  64 mW

A semiconductor is known to have an electron concentration of $8\times {10}^{13}$ cm^-3 and a hole concentration of $5\times {10}^2$ cm^-3. The semiconductor is:

1.  n-type

2.  p-type

3.  intrinsic

4.  insulator

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

The given electrical network is equivalent to 

1. AND gate 

2. OR gate

3. NOR gate

4. NOT gate 

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

1. 200 and 1000

2. 15 and 200

3. 150 and 15000

4. 20 and 2000