BS(1) Subject: BSIT University of Sargodha 1st Term final Exam 2015 Course:Basic Electronics (PHY-2210) Time Allowed: 2:30 Hours

BS(1)

Subject: BSIT

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

X. What is avalanche Breakdown in reverse biased P-N Junction?

Z. Can a transformer operate on DC?

3. Define drift current in good conductor

Define threshold voltage. Give its value for Si and Ge/Junction?

Why Collector-Base Junction is always reverse biased?

& Which factors control the capacitance of the capaciter?

What is the basic principle behind the propagation of light in optical fibre?

3. Write down two examples of nonlinear resistor

. Define Silicon Controlled Rectifier (SCR)?

Kat®

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

c. Mention at least five different energy sources

12. Briefly describe how electrons are multiplied in photomultiplier tube?

3. Draw symbols of an air-core and ad irón-core inductor?

14. Why we use series voltage dividers circuits?

15. What is difference between electron and hole?

16. Do pure semiconductors obey Ohm's law?

Subjective Part

(4 x 12 =

48)

(16 x 2-32)

0. 2(a) Discuss Capacitance of Capacitor in sertes and parallel connection?

Calculate the inductive reactance offered by a coil of inductance 250uH to radio

frequeney currents of frequencies

(i) IMHz (il) 1OMHz

I's Define parallel circuit? Explain characteristics of a parallel resistive circuit?

(6)

(6)

12V

In the circuit of Fig 1, Find

Fig 1

i.

Circuit current

ii.

Voltage of point A with respect to ground +12

lit.

Voltage of point B with respecto A -12

(6)

Q. 4(a) Explain principle, construction, working and advantages of Bulk type photoconductive

cell.

(12)

96 Explain construction and working of fall wave rectifier using Centre tapped trans formor.

• 465

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

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

(1) Voltage V2 (il) current Iz

(4)

Q. 7

Draw a NPN Transistor circuit in common collector configuration and discuss its input,

output characteristics.

(12)

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