In the figure, the V BB supply can be varied from 0 V to 5 . 0 V . The transistor has β dc = 250 and R B = 100 Ω , R C = 1 kΩ , V CC = 5 . 0 V . Assume that when the transistor is saturated, V CE = 0 V and V BE = 0 . 8 V . Calculate the minimum base current and input voltage for which the transistor will reach saturation.

∴ V C E = V C C - I C R C Given , V C C = 5 V Therefore, l C = V C C R C = 5 V 1 kΩ = 5 mA And I B = I C β = 5 mA 250 = 20 μA

Explain how a deplection region is formed in a junction diode.

A depletion region forms instantaneously across a p–n junction. It is most easily described when the junction is in thermal equilibrium or in a steady state: in both of these cases the properties of the system do not vary in time; they have been called dynamic equilibrium. Electrons and holes diffuse into regions with lower concentrations of them, much as ink diffuses into water until it is uniformly distributed. By definition, the N-type semiconductor has an excess of free electrons (in the conduction band) compared to the P-type semiconductor, and the P-type has an excess of holes (in the valence band) compared to the N-type. Therefore, when N-doped and P-doped semiconductors are placed together to form a junction, free electrons in the N-side conduction band migrate (diffuse) into the P-side conduction band, and holes in the P-side valence band migrate into the N-side valence band.

Define small signal current gain of a transistor in common emitter configuration.

Small signal current gain is the ratio of a change in IC to a change in IB, with the initial IC value specified. On the curve tracer, hfe is checked by measuring the difference in IC between two values of IB. The change in collector current is divided by the change in base current to arrive at hfe.

Write two points of advantages of FM broadcasting over AM broadcasting.

The amplitude of FM is constant which makes it independent of the modulation deption, while in AM modulation depth directs the transmitted power. Noise in FM is reduced to a large extent by employing amplitude limiters to remove the amplitude variations caused by noise.

Using block diagrams, name the segments of general communication system.

The communication system is a system which describes the information exchange between two points. The process of transmission and reception of information is called communication. The major elements of communication are the Transmitter of information, Channel or medium of communication and the Receiver of information.

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12th Manipur Board

IMPORTANT

Earn 100

What are the basic conditions of biasing the emitter-base and collector-base junctions of a transistor for its proper functioning?

Important Questions on Semiconductor Electronics: Materials, Devices and Simple Circuits

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12th Manipur Board

IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR PHYSICS>Chapter 14 - Semiconductor Electronics: Materials, Devices and Simple Circuits>Manipur Board-2018>Q 4

Differentiate between

n -

type and

p -

type extrinsic semiconductors by giving two points.

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IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR PHYSICS>Chapter 14 - Semiconductor Electronics: Materials, Devices and Simple Circuits>Manipur Board-2018>Q 5

For a transistor the emitter current is

0.505 mA

and the base current is

5.0 μA

. The collector is

MEDIUM

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IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR PHYSICS>Chapter 14 - Semiconductor Electronics: Materials, Devices and Simple Circuits>Manipur Board-2018>Q 6

The device fitted in the satellite which receives signals from the earth station and transmits them in the different directions is called

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12th Manipur Board

IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR PHYSICS>Chapter 14 - Semiconductor Electronics: Materials, Devices and Simple Circuits>Manipur Board-2019>Q 7

Identify the logic gate and write its Boolean expression.

Question Image

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IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR PHYSICS>Chapter 14 - Semiconductor Electronics: Materials, Devices and Simple Circuits>Manipur Board-2019>Q 8

Draw a neat labelled circuit diagram showing the use of an

n - p - n

transistor as a common emitter amplifier.

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EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR PHYSICS>Chapter 14 - Semiconductor Electronics: Materials, Devices and Simple Circuits>Manipur Board-2019>Q 9

What is sky wave propagation? Mention the frequency range used by this type of propagation.

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EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR PHYSICS>Chapter 14 - Semiconductor Electronics: Materials, Devices and Simple Circuits>Manipur Board-2019>Q 10

In a transistor,

I_{C} = 0.98, I_{B} = 20 μA

. Find

(i)

α

and

(ii) β

Of the transistor.

MEDIUM

12th Manipur Board

IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR PHYSICS>Chapter 14 - Semiconductor Electronics: Materials, Devices and Simple Circuits>Manipur Board-2019>Q 11

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A zener diode of rating $100 mW$ is to be used as a voltage regulator. If the zener diode has the breakdown voltage of $5 V$ and it has to regulate voltage which fluctuate between $3 V$ and $7 V$ , what should be the value of $R_{S}$ for safe operation.

What are the basic conditions of biasing the emitter-base and collector-base junctions of a transistor for its proper functioning?

Important Questions on Semiconductor Electronics: Materials, Devices and Simple Circuits

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