The conductivity of an n-type semiconductor whose density of conduction electrons is ${\mathrm{n}}_{\mathrm{e}}$, Density of holes is ${\mathrm{n}}_{\mathrm{h}}$, Mobility of conduction electrons is ${\mathrm{m}}_{\mathrm{e}}$and Mobility of holes is ${\mathrm{m}}_{\mathrm{h}},$ will be

1.  $\mathrm{e}\left[{\mathrm{n}}_{\mathrm{e}}{\mathrm{m}}_{\mathrm{h}}<mspace\; width="1em"></mspace>+<mspace\; width="1em"></mspace>{\mathrm{n}}_{\mathrm{e}}{\mathrm{m}}_{\mathrm{e}}\right]<mspace\; width="1em"></mspace>$

2.  $\mathrm{e}\left[{\mathrm{n}}_{\mathrm{e}}{\mathrm{m}}_{\mathrm{e}}<mspace\; width="1em"></mspace>+<mspace\; width="1em"></mspace>{\mathrm{n}}_{\mathrm{h}}{\mathrm{m}}_{\mathrm{e}}\right]<mspace\; width="1em"></mspace><mspace\; width="1em"></mspace>$

3.  ${\mathrm{en}}_{\mathrm{e}}\left[{\mathrm{m}}_{\mathrm{e}}<mspace\; width="1em"></mspace>+<mspace\; width="1em"></mspace>{\mathrm{m}}_{\mathrm{h}}\right]<mspace\; width="1em"></mspace><mspace\; width="1em"></mspace>$

4.  $\mathrm{e}\left[{\mathrm{n}}_{\mathrm{e}}{\mathrm{m}}_{\mathrm{e}}<mspace\; width="1em"></mspace>+<mspace\; width="1em"></mspace>{\mathrm{n}}_{\mathrm{h}}{\mathrm{m}}_{\mathrm{h}}\right]<mspace\; width="1em"></mspace>$

A transistor is used in common emitter mode in an amplifier circuit. When a signal of 10 mV is added to the base-emitter voltage, the base current changes by 15 $\mu$A and the collector current changes by 1.5 mA. The current gain \(\beta\) will be:

1.  50

2.  48

3.  100

4.  200

$\mathrm{In}<mspace\; width="1em"></mspace>\mathrm{the}<mspace\; width="1em"></mspace>\mathrm{given}<mspace\; width="1em"></mspace>\mathrm{circuit}<mspace\; width="1em"></mspace>\mathrm{power}<mspace\; width="1em"></mspace>$
$\mathrm{developed}<mspace\; width="1em"></mspace>\mathrm{in}<mspace\; width="1em"></mspace>1\mathrm{k\Omega }<mspace\; width="1em"></mspace>\mathrm{resistor}<mspace\; width="1em"></mspace>\mathrm{is}$

1.  36 mW

2.  12 mW

3.  144 mW

4.  64 mW

In a common emitter transistor amplifier, the audio signal vlotage across the collector is 3V. The resistance of collector is 3k$\Omega$. If current gain is 100 and the base resistance is 2k$\Omega$, the voltage and power gain of the amplifier is 

(1) 200 and 1000

(2) 15 and 200

(3) 150 and 15000

(4) 20 and 2000

What is the output Y in the following circuit, when all the three inputs A,B,C are first 0 and then 1 ?

1. 0,1                   2. 0,0 

3. 1,0                   4. 1,1

To get output 1 for the following circuit, the correct choice for the input is

(1) $A=1,<mspace\; width="1em"></mspace>B=0,<mspace\; width="1em"></mspace>C=0$       

(2) $A=1,<mspace\; width="1em"></mspace>B=1,<mspace\; width="1em"></mspace>C=0$

(3) $A=1,<mspace\; width="1em"></mspace>B=0,<mspace\; width="1em"></mspace>C=1$       

(4) $A=0,<mspace\; width="1em"></mspace>B=1,<mspace\; width="1em"></mspace>C=0$

Which logic gate is represented by the following combination of logic gates?
         
1. OR
2. NAND
3. AND
4. NOR

In the given figure, a diode D is connected to an external resistance R = 100 Ω  and an e.m.f of 3.5 V. If the barrier potential developed across the diode is 0.5 V, the current in the circuit will be


1. 30mA

2. 40mA

3. 20mA

4. 35mA

The barrier potential of a p-n junction depends on

(i)type of semiconductor material

(ii)amount of doping

(iii)temperature

Which one of the following is correct

1. (i) and (ii)only

2. (ii) only

3. (ii) and (iii)only

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