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

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

To get an output Y=1 in given circuit, which

of the following input will be correct ?

    A     B      C                  

1. 1     0       0             
2. 1     0      1
3. 1      1     0             
4. 0     1      0

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

The device that can act as a complete electronic circuit is

1. Junction diode

2. Integrated circuit

3. Junction transistor

4. Zener diode

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

A p-n photodiode is made of a material with a band gap of 2.0 eV. The minimum frequency of the radiation that can be absorbed by the material is nearly

1. $10\times {10}^{14} Hz$                             
2. $5\times {10}^{14} Hz$
3. $1\times {10}^{14} Hz$                               
4. $20\times {10}^{14} Hz$

The circuit is equivalent to

1. AND gate                              2. NAND gate

3. NOR gate                              4. OR gate 

The reverse biasing in a PN junction diode

1. Decreases the potential barrier

2. Increases the potential barrier

3. Increases the number of minority charge carriers

4. Increases the number of majority charge carriers