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**Q.1. The correct Boolean operation represented by the circuit diagram drawn is: (2019)**

**A: ANDB: ORC: NANDD: NORAns: **C

Solution:

From the given logic circuit LED will glow,

when voltage across LED is high.

Truth Table

This is out put of NAND gate.**Q.2. For a p-type semiconductor, which of the following statements is true ? (2019)A: Electrons are the majority carriers and trivalent atoms are the dopants.B: Holes are the majority carriers and trivalent atoms are the dopants.C: Holes are the majority carriers and pentavalent atoms are the dopants.D: Electrons are the majority carriers and pentavalent atoms are the dopants.Ans: **B

Solution:

In p-type semiconductor, an intrinsic semiconductor is doped with trivalent impurities, that creates deficiencies of valence electrons called holes which are majority charge carriers.

A:

B:

C:

D:

Ans: B

Solution:

**Q.4. ****In a p-n junction diode, change in temperature due to heating :-A: affects only reverse resistanceB: affects only forward resistanceC: does not affect resistance of p-n junctionD: affects the overall V - I charaterstics of pn junction Ans: **D

Solution:

Affects the overall V - I characteristic of p-n junction.

On heating, a number of electron - hole pairs increase, so overall resistance of diode will change.

Hence, forward biasing and reversed biasing both are changed.

A: 15 and 200

B: 150 and 15000

C: 20 and 2000

D: 200 and 1000

Ans:

Solution:

**Q.6. ****The given electrical network is equivalent to: (2017)**

**A: OR gateB: NOR gateC: NOT gateD: AND gateAns: **B

Solution:

**Q.7. ****Which one of the following represents forward bias diode ? (2017)A:**

B:

C:

D:

**Ans: **D

Solution:

**Q.8.**** To get output 1 for the following circuit, the correct choice for the input is : (2016)A: A = 1, B = 0, C = 1B: A = 0, B =1, C = 0C: A = 1, B = 0, C = 0D: A = 1, B = 1, C = 0Ans: **A

Solution:

The resultant boolean expression of the above logic circuit is given by,

Y = (A+B).C

Using the inputs given in the options,

If A = 0, B = 0,C = 0, we have

Y = (0+0).0

i.e., Y = 0

If A = 1, B = 1, C = 0, then we have

Y = (1+1).0

i.e., Y = 1.0 = 0

If A = 1, B = 0, C = 1, then

Y = (1+0).1

i.e., Y = 1.1 = 1

If A = 0, B = 1, C = 0, then

Y = (0+1).0

i.e., Y = 1.0

Y = 0

Therefore, output Y = 1 only when inputs A = 1, B = 0 and C = 1.

**A: 10 ^{-3} AB: 0 AC: 10^{-2} AD: 10^{-1} AAns: **C

Solution:

I = Î”V/R = 4-(-6)/ 10

A: 4, 3.69

B: 4, 3.84

C: 3.69, 3.84

D: 4, 4

Ans:

Solution:

Given,

Resistance across load, R

Voltage drop across load, V

Input resistance of the circuit, R

Collector current is given by,

then the output across R_{L} will be : (2015)

A:

B:

C:

D:

**Ans:** A

As it is forward biased so it takes positive value. Hence, option (A) is correct.

A: NOR

B: OR

C: NAND

D: AND

Ans: D

Solution:

Truth table

This correspond to AND gate**Q.13. ****The given graph represents Vâˆ’I characteristic for a semiconductor device.**

**Which of the following statement is correct ? (2014)A: It is for a photodiode and points A and B represent open circuit voltage and current,respectivelyB: It is for a LED and points A and B represent open circuit voltage and short circuit current, respectivelyC: It is Vâˆ’I characteristic for solar cell where, point A represents open circuit voltage andpoint B short circuit currentD: It is for a solar cell and points A and B represent open circuit voltage and current,respectivelyAns: **C

(a) type of semi conductor material

(b) amount of doping

(c) temperature

Which one of the following is correct?

A: (b) and (c) only

B: (a),(b) and (c)

C: (a) and (b) only

D: (b) only

Barrier potential depends on the material used to make p-n junction diode (whether it is Si or Ge).

It should also depend on the amount of doping due to which the number of majority charge carriers will change. Also, it depends on temperature due to which the number of minority carriers will change.

Barrier potential depends on the material used to make p-n junction diode (whether it is Si or Ge).

It should also depend on the amount of doping due to which the number of majority charge carriers will change. Also, it depends on temperature due to which the number of minority carriers will change.

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