The following configuration of the logic gate is equivalent to

1.  NAND gate

2.  XOR gate

3.  OR gate

4.  NOR gate

Three ideal diodes are connected to the battery as shown in the circuit. The current supplied by the battery is

1.  Zero

2.  4A

3.  2A

4.  6A

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

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.

A transistor is operated in common emitter configuration at ${\mathrm{V}}_{\mathrm{c}} = 10\mathrm{V}.$ 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

1.  100

2.  99

3.  10

4.  9

When a p-n junction is forward biased, then:

1.  the depletion region becomes thick.

2.  the p-side is at a higher potential than n side.

3.  the current flowing is zero.

4.  the effective resistance is of the order of \(10^6 ~\Omega\).

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

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

1.  Electron is 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.

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

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.  ${\mathrm{n}}_1 = {\mathrm{n}}_{\mathrm{e}} = {\mathrm{n}}_{\mathrm{h}}$

2.  ${{\mathrm{n}}_{\mathrm{i}}}^2 = {\mathrm{n}}_{\mathrm{e}}{\mathrm{n}}_{\mathrm{h}}$

3.  ${\mathrm{n}}_{\mathrm{h}} >> {\mathrm{n}}_{\mathrm{e}}$

4.  ${\mathrm{n}}_{\mathrm{h}} << {\mathrm{n}}_{\mathrm{e}}$