Transfer characteristic [output voltage $\left(V_{\mathrm{o}}\right)$ vs input voltage $\left(V_i\right)$] for a base biased transistor in CE configuration is as shown in the figure. For using transistor as a switch, it is used:
                     

1. in region III

2. both in region (I) and (III)

3. in region II

4. in region I

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

Symbolic representation of four logic gates

are shown as

(i) 

(ii) 

(iii) 

(iv) 

Pick out which ones are for AND, NAND and 

NOT gates, respectively.

(a) (iii), (ii)and (i)

(b) (iii), (ii) and (iv)

(c) (ii), (iv) and (iii)

(d) (ii), (iii) and (iv)

If a small amount of antimony is added to germanium crystal

(1) the antimony becomes an acceptor atom

(2) there will be more free electrons than holes in the semiconductor

(3) its resistance is increased

(4) it becomes a p-type semiconductor

In forward biasing of the p-n junction 

A transistor is operated in common emitter configuration at ${\mathrm{V}}_{\mathrm{C}}=2 \mathrm{V}$ such that a change in the base current from $100 \mathrm{\mu A}$ to $300 \mathrm{\mu A}$ produces a change in the collector current from $10 \mathrm{mA}$ to $20 \mathrm{mA}$. The current gain is 

1. 75                                               2. 100

3. 25                                                4. 50

In the following figure, the diodes which are forward biased, are

1.  III and IV only

2.  I and III only

3.  II only

4.  II and IV only

A Zener diode, having breakdown voltage equal to 15 V, is used in a voltage regulator circuit, as shown in the figure. The current through the diode is:

1. 10 mA

2. 15 mA

3. 20 mA

4. 5 mA

Which one of the following statement is false?

(1) Pure Si doped with trivalent impurities gives a p-type semiconductor 

(2) Majority carries in a n-type semiconductor are holes

(3) Minority carries in a p-type semiconductor are electrons

(4) The resistance of intrinsic semiconductor decreases with increase of temperature 

To get an output Y =1 from the circuit shown below, the input must be

        A     B     C

(1)   0      1     0

(2)   0      0     1

(3)   1      0     1

(4)   1      0     0