Basic Electronics AD/BS 1 Semester/Term UOS — University of Sargodha 2015

BS(CS)

Subject: BS(CS)

University of Sargodha

1st Term final Exam 2015

Course:Basic Electronics (PHY-2210)

Time Allowed: 2:30 Hours

Maximum Marks: 80

Note: Objective part is compulsory. Attempt any four questions from subjective parts.

Objective Part

Q. 1 Write short answers of the following questions in 2-3 lines only

(16 x 2 =

32)

What is zero reference level? why we need it during voltage measurements at different

points in electric circuit

Differentiate transition capacitance and diffusion capacitance?

Why PIN Photodiodes have faster response than even the P-N Photodiode?

Why we need filters in the electronics circuits?

Which factors control the capacitance of the capacitor?

The colour of light emitted by LED depends on what?

What is effect of temperature on barrier voltage?

• Why electrons have greater mobility than holes in a semiconductor material?

Distinguish between drift speed and Fermi speed?

0) Explain effect of doping on semiconductor

1 In an optical fibre why refractive index of core is kept higher than cladding?

Draw symbols of an air-core and ad iron-core inductor?

5) Under what condition a transistor can operate in active region.

4) Define Solar cell? Draw its symbol.

) What are carrier waves?

What is Amplitude modulation?

Subjective Part. (4 x 12 =

48)

* 2(a) Define inductor. Explain Mutual Inductance in detail.

Calculate the inductive reactance offered by a coil of inductance 250pH 1o radio

frequency currents of frequencies

(i) IMHz (il) 10MHz

Q.3

Define series circuit? Explain characteristics of a series resistive circuit?

(G)

A 12V battery of negligible interal resistance is connected across a parallel combination

of 4K, 6K, and 12K resistors. Compute

(i) Combined circuit resistance

(il) Current supplied by the battery

(iii). Power supplied by the battery

(6)

4(a)What is Transformer? Explain principle, construction, working of Transformer (8)

A power transformer has 100 primary turns and 600 secondary turns. If primary voltage

is 120V and full load primary current is 12A, Find secondary

(i) Voltage V½ (il) current Iz

What is P-N Junction? Explain Forward and Reverse Voltage Current Characteristics of a

P-N junction

6(a) Explain Transistor biasing for the proper working of a PNP and NPN transistor

(G)

Following readings are obtained in transistor circuit of CB Configuration.

(6)

Ie = 1mA, a = 0.95

Find the values of Is and le

Define Modulation? Discuss Frequency modulation in detail.

(12)