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 

The device that can act as a complete electronic circuit is

1. Junction diode

2. Integrated circuit

3. Junction transistor

4. Zener diode

A common emitter amplifier has a voltage gain of 50, an input impedance of 100$\mathrm{\Omega }$ and an output impedance of 200$\mathrm{\Omega }$. The power gain of the amplifier is-

1. 500         

2. 1000

3. 1250       

4. 50

The following figure shows a logic gate circuit with two inputs A and B and the output Y. The voltage waveforms of A, B and Y are as given

The logic gate is 

(1) $\mathrm{NOR}$ gate                                                 

(2) $\mathrm{OR}$ gate

(3) $\mathrm{AND}$ gate                                                 

(4) $\mathrm{NAND}$gate

For transistor action:

Which of the following pairs of statements is correct?
1. (d) and (a)
2. (a) and (b)
3. (b) and (c)                                       
4. (c) and (d)

A p-n photodiode is fabricated from a semiconductor with a band gap of $2.5 \mathrm{eV}.$ It can detect a signal of wavelength 

(1) $6000 \stackrel{\circ }{\mathrm{A}}$                                   
(2) $4000 \mathrm{nm}$
(3) $6000 \mathrm{nm}$                                 
(4) $4000 \stackrel{\circ }{\mathrm{A}}$

The symbolic representation of four logic gates 

                           (i)                                                                              (ii)

                           (iii)                                                                              (iv)

The logic symbols for $\mathrm{OR},$ $\mathrm{NOT}$ and $\mathrm{NAND}$ gates are respectively

(a)    (iii), (iv), (ii)                                            (b)   (iv), (i), (iii)

(c)    (iv), (ii), (i)                                              (d)   (i), (iii), (iv)