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 

In a PN-junction diode:

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

The electrical resistance of depletion layer is large because:

1. It has no charge carriers

2. It has a large number of charge carriers

3. It contains electrons as charge carriers

4. It has holes as charge carriers

In an NPN transistor the collector current is 24 mA. If 80% of electrons reach collector its base current in mA is

1. 36                       2. 26
3. 16                       4. 6

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

of the following input will be correct ?

      A     B      C                   A     B     C

1.  1     0       0             2.  1     0     1

3. 1      1       0             4.  0     1     0