# NEET (NTA)-National Eligibility cum Entrance Test (Medical) Physics: Questions 1693 - 1697 of 2320

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## Passage

Doping changes the Fermi energy of a semiconductor. Consider silicon, with a gap of 1.11 eV between the top of the valence bond and the bottom of the conduction band. At 300K the Fermi level of the pure material is nearly at the mid-point of the gap. Suppose that silicon is doped with donor atoms, each of which has a state 0.15 eV below the bottom of the silicon conduction band, and suppose further that doping raises the Fermi level to 0.11 eV below the bottom of that band.

## Question number: 1693 (2 of 3 Based on Passage) Show Passage

Edit
MCQ▾

### Question

For doped silicon, calculate the probability that a state at the bottom of the silicon conduction band is occupied? (e 4.254 = 70.38)

### Choices

Choice (4)Response

a.

1.40 ⨯ 10 -2

b.

10.5 ⨯ 10 -2

c.

5.20 ⨯ 10 -2

d.

14 ⨯ 10 -2

## Question number: 1694 (3 of 3 Based on Passage) Show Passage

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MCQ▾

### Question

Calculate the probability that a donor state in the doped material is occupied?

### Choices

Choice (4)Response

a.

0.008

b.

8.2

c.

0.08

d.

0.824

## Question number: 1695

Edit
MCQ▾

### Question

 P Q X 0 0 0 0 1 0 1 0 0 1 1 1

### Choices

Choice (4)Response

a.

OR

b.

NOR

c.

NAND

d.

AND

## Question number: 1696

Edit
MCQ▾

### Question

Which of the following are false?

(1) Common base transistor is commonly used because current gain is maximum

(2) Common collector is commonly used because current gain is maximum

(3) Common emitter is the least used transistor

(4) Common emitter is commonly used because current gain is maximum

Select the correct answers and mark it according to the following codes.

### Choices

Choice (4)Response

a.

1,2 and 3 are correct

b.

1 and 2 are correct

c.

2 and 4 are correct

d.

1 and 3 are correct

## Question number: 1697

Edit
Assertion-Reason▾

### Assertion (Ꭺ)

De-morgen’s theorem may be explained by the following circuit

### Reason (Ꭱ)

In the following circuit, for output 1 inputs A, B, C are 1,0, 1.

### Choices

Choice (4)Response

a.

Ꭺ is false but Ꭱ is true

b.

Both Ꭺ and Ꭱ are true but Ꭱ is NOT the correct explanation of Ꭺ

c.

Both Ꭺ and Ꭱ are true and Ꭱ is the correct explanation of Ꭺ

d.

Ꭺ is true but Ꭱ is false

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