# Electronics [Optionals IAS Mains Physics]: Questions 1 - 8 of 22

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## Question 1

Appeared in Year: *2011 (IFS)*

### Describe in Detail

Essay▾Explain the basic structure and operation of an channel FET.

How FET acts as an amplifier? Explain.

### Explanation

- The FET have three terminals: Source , Gate and Drain . The FET controls the flow of current from source to drain by applying voltage across the gate and source terminals. Therefore, this device is also called voltage controlled devices.
- FETs are composed of PN-junction or Schottky junction, therefore they are called JFET or MESFET (Metal Semicondu…

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## Question 2

Appeared in Year: *2011 (IFS)*

### Describe in Detail

Essay▾What are intrinsic and extrinsic semi – conductors? Explain.

How are type and type semiconductors obtained?

### Explanation

**Intrinsic Semiconductors**:

- Intrinsic semiconductors are pure semiconducting material and no impurity atoms are added to them. The conductivity of the intrinsic semiconductor are at the room temperature is zero. It means the valence band of the intrinsic semiconductor is completely filled and conduction band is completely empty at room temperature.
- The…

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## Question 3

Appeared in Year: *2011 (IFS)*

### Describe in Detail

Essay▾Using OP – AMPs design an analog circuit to solve the following differential equation:

With,

### Explanation

Here, the given second order differential equation is,

The analog circuit consist of op – amp for equation (1) is designed as,

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## Question 4

Appeared in Year: *2009*

### Describe in Detail

Essay▾List the characteristics of an ideal op-amp. Write the expression for the output voltage in terms of input voltages and resist tance values.

(20 Marks)

### Explanation

The ideal op-amp has these characteristics:-

(i) Input impedance (differential or common mode) = infinity and so zero input current.

(ii) Output impedance (open loop) = 0

(iii) Voltage gain = infinity

(iv) Common mode voltage gain = 0

(v) When both input are at same voltage (zero ″ offset voltage)

(vi) Output can change instantaneously (infinite slow r…

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## Question 5

### Write in Short

Short Answer▾Show that the circuit shown below is an exclusive OR gate.

(10 Marks)

## Question 6

Appeared in Year: *2015*

### Write in Short

Short Answer▾Simplify the logical expression (10 Marks)

## Question 7

Appeared in Year: *2003*

### Describe in Detail

Essay▾In the following circuit, show that the stability factor S is given by

Where

(20 Marks)

### Explanation

It is desirable and necessary to keep constant in the face of variations of (sometimes represents as ) . The extent to which a biasing circuit is successful in achieving this goal is measured by stability factor S. It is defined as the rate of change of collector current w. r. t. the collector leakage current at content and is called stabilit…

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## Question 8

### Explanation

- The Boolean equation for is .

- The Boolean equation for is .

The first equation describes a NOR gate, and the second equation a bubbled AND gate. Since the outputs are equal for the same inputs, we can equate the right-hand members to get

The identity is known as De Morgan՚s first theorem. In words, it says the complement of a sum equ…

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