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.

1. (iii), (ii)and (i)

2. (iii), (ii) and (iv)

3. (ii), (iv) and (iii)

4. (ii), (iii) and (iv)

In forward biasing of the p-n junction 

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 

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

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

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

The figure shows a logic circuit with two inputs A and B and the output C. The voltage wave forms across A, B and C are as given. The logic circuit gate is 

1. OR gate                                         
2. NOR gate
3. AND gate                                       
4. NAND gate

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