How many NAND gates are used to form AND gate?

1.  1

2.  2

3.  3

4.  4

A Ge specimen is doped with Al. The concentration of acceptor atoms is $={10}^{21} \mathrm{atoms}/{\mathrm{m}}^3$. Given that the intrinsic concentration of electrons in the specimen is ${10}^{19}/m^3$. The new electron concentration is

1.  ${10}^{17}/m^3$

2.  ${10}^{15}/m^3$

3.  ${10}^4/m^3$

4.  ${10}^2/m^3$

A semiconductor is known to have an electron concentration of $8\times {10}^{13} per c{m}^2$ and hole concentration $5\times {10}^{12} per c{m}^3$. The semiconductor is

1.  n type

2.  p type

3.  Intrinsic 

4.  None of these 

An n-p-n transistor is biased to use it as an amplifier. Which of the following statements is not correct?

1. The electrons go from emitter region to base region.

2. The electrons go from base region to collector region

3. The electrons go from collector region to base region

4. The holes go from base region to emitter region

Figure shows the connections of two ideal diodes and two capacitors C and 2C. A 120 volt battery is connected to the input terminals with a at positive potential and b at lower potential. The output voltage across cd is

1.  60 V

2.  40 V

3.  30 V

4.  20 V

In the circuit shown in the figure, the input voltage V_i is 20 V, V_BE = 0, and V_CE = 0. The values of I_B, I_C and $\beta$ are given by:
           

1. ${\mathrm{I}}_{\mathrm{B}}$ $=$ $40$ $\mathrm{\mu A},$ ${\mathrm{I}}_{\mathrm{c}}$ $=$ $10$ $\mathrm{mA},$ $\mathrm{\beta }$ $=$ $250$

2. ${\mathrm{I}}_{\mathrm{B}}$ $=$ $25$ $\mathrm{\mu A},$ ${\mathrm{I}}_{\mathrm{c}}$ $=$ $5$ $\mathrm{mA},$ $\mathrm{\beta }$ $=$ $200$

3. ${\mathrm{I}}_{\mathrm{B}}$ $=$ $20$ $\mathrm{\mu A},$ ${\mathrm{I}}_{\mathrm{c}}$ $=$ $5$ $\mathrm{mA},$ $\mathrm{\beta }$ $=$ $250$

4. ${\mathrm{I}}_{\mathrm{B}}$ $=$ $40$ $\mathrm{\mu A},$ ${\mathrm{I}}_{\mathrm{c}}$ $=$ $5$ $\mathrm{mA},$ $\mathrm{\beta }$ $=$ $125$

The given circuit has two ideal diodes connected as shown in the figure below. The current flowing through the resistance \(R_1\) will be:
   
1. \(2.5~\text{A}\)
2. \(10.0~\text{A}\)
3. \(1.43~\text{A}\)
4. \(3.13~\text{A}\)