Basic Electronics BSSE/CS/IT UOS — University of Sargodha 2019

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Unirscalls of Sargosha

1S 1' Lec Loamination 2919

Tlane Allowed: 2:30 Hours

Mastmem Marks: 60

Note: Objectire part is compulary. Altempt nay three quentione from ushjeetire part.

Objective Part

(Compulsory)

Q.1.

Write short answers of the following in 2-3 lines each

(2*16)

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(i) Define a linear resistor? Draw its V-l curve?

(il). Why electrons have greater mobility than holes in a semiconductor material?

(ai) What is the effect of doping on width of depletion layer?

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(iv) Draw schematic energy hand diagram, of a P-type extrinsic semiconductor?

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(v) What is Zener breakdown in reverse biased P-N junction?

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(vi) Do pure semiconductors obey ohms law?

(vii) Draw symbols of an air-core and an iron-core inductor.

(viii) Why optical fibres are better than metallic wires?

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(ix) What are thermally generated charge carriers?

(x) In a transistor why emitter is heavily doped? and collector is lightly doped

(x) Describe a circuit which provides continuously varying potentials?

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(xii) Differentiate between primary and secondary cells.

} (xil) Define capacitance of a capacitor and its unit.

(xiv) What should be the features of outside protection provided to an optical fiber

4(xv) Ten resistors each having resistance 10 ohm are connected in parallel. What is their equivalen!

resistance?

L(xvi) What is LED?

Q.2.

Q.3.

Q.4.

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Q6

Subjective Part

(16*3)

(a) How P-N juactio

ote forward and reverse blased? Draw VI characteristic curve for PN

junction diode

(b) What are intrinsic semiconductors? What is their behaviour at OK and at room temperature (i.e

300K) What is their response to electric field

(a) What is photomultiplier tube? Write theory involved in photomultiplier tube.

(b) A 12 volt battery of negligible internal resistance is connected across a parallel combination ol

4K, 6K and 12K resistors. Compute

i) Combined circuit resistance 2

i) Current supplied by the battery 6

iii) Power supplied by the battery 72

(a) What is rectification? Which characteristic of a diode is used in rectification? Explain its types

(b) How pulsating de can be converted in to pure do by using an inductor filter?

(a) Define modulation, Demodulation and carrier wave? There are how many methods of

Modulation? Why frequency modulation is advantageous as compared to amplitude modülation?

(b) Explain structure of an optical fibre with the help of a diagram.

(a) What is a transformer? How it works (core type transformer)? what is voltage transformation

ratio? What is condition for ideal transformer?

(b) A power transformer has 100 primary turns and 600 accondary turns. If primary voltage is 120

roit and full loed primary current is I; Amp, find secondary voltage V, and Secondary current I:

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