৩৭তম বিসিএস ইইই লিখিত প্রশ্ন
জলতরঙ্গ
বিষয় কোড : ৮৯১
নির্ধারিত সময়-৪ ঘন্টা
পূর্ণমান-২০০
দ্রষ্টব্য-বাংলা অথবা ইংরেজি যে কোন একটিভাষায় উত্তর দিতে পারবেন। তবে একই
বিষয়ে বাংলা এবং ইংরেজি দুটি ভাষায় উত্তর দিতে পারবেন না। টেকনিকাল
শব্দগুলো ইংরেজিতে লেখা যাবে। প্রার্থীগণকে পার্ট-১ থেকে ১ নং প্রশ্নসহ যে
কোন ছটি এবং পার্ট-২ থেকে ৯ নং প্রশ্নসহ যে কোন ছটি প্রশ্নের উত্তর দিতে
হবে। প্রত্যেক প্রশ্নের মান প্রশ্নের শেষ প্রান্তে দেখানো হয়েছে।
পার্ট-১
(১ নং প্রশ্নসহ যে কোন ছটি প্রশ্নের উত্তর দিতে হবে)
১. (a) Describe the condition for parallel operation of two
generators.
(b) State how does the rotor of an induction motor (3-φ)
rotate?
(c) What is modulation and what are the types of
modulation?
(d) What are the application of SCR circuits?
২. (a) Discuss the factors that controls the speed of a d.c. motor.
(b) A 250v dc shunt motor has armature resistance of 0.25Ω,
on load it takes an armature current of
50A and runs at 750 rpm. If the flux of motor is reduced by
10% without changing the load
torque, find the new speed of the motor.
৩. (a) Explain how BJT works as switch. Draw the small signal hybrid model
of a BJT.
(b) Draw the circuit diagram of a BJT emitter
stabilized bias circuit and find the expressions of I_B
and V_CE. Where the symbols have their usual
meaning.
৪. (a) Draw the following wave shapes for the given circuit :
(i) Output voltage
(ii) Input connect.
(b) Design a logic circuit using only one type of gates to realize the
following expression :
Y=(ā+b+ē)(a+ē)
(c) Draw a non-inverting Amplifier using an operation Amp.
5. (a) For the circuit shown in below. Calculate the value of R that will
make the energy stored in the
capacitor the same as that stored in the inductor under dc
conditions.
(b) A three phase line has an impedance of 1+j3Ω per phase.
The line feeds a balanced delta
connected load. Which absorbs a
total complex power of 12-j5 KVA. If the line voltage at the load
end has a magnitude of 240v, calculate the
magnitude of the line voltage at the source end and the
source power factor.
6. (a) What is the significant difference between the construction of an
enhancement type MOSFET
and a depletion type MOSFET? Briefly describe the basic
operation of an enhancement type
MOSFET?
(b) Design and op. amp circuit with inputs ϑ1 and ϑ2 such
that output
ϑ0 = 5ϑ1 + 3dϑ2 /dt
7. (a) Draw the I-V characteristics of a filament lamp and a diode, and
compare their characteristics.
(b) Explain how a DC power supply can be made from AC
source.
(c) Explain how a 'zene diode' stabilizes the voltage of a
circuit.
(d) Explain how a crystal diode works as a rectifier.
8. Write short notes on any four of the following :
(a) TRIAC
(b) Digital memory
(c) Compound D.C. motor
(d) Time division multiplexing
(e) Phase sequence
(f) Short circuit faults.
পার্ট-২
(৯ নং প্রশ্নসহ যে কোন ৫ টি প্রশ্নের উত্তর দিতে হবে)
9. (a) What are the objectives of Auto Generation control?
(b) Express the fault audition for line to line fault on an
unloaded generator.
(c) Define single mode and multimode optical fiber.
(d) What is the difference between unregulated and regulated
power supplies?
10. (a) Discuss the merits and demerits of a hydro-electric plant?
8
(b) Why is the load on a power station variable? What are the effects of
variable load on the operations of the power station?
11. (a) Calculate the data rate of a bipolar signal if the fundamental
frequency is 10KHz.
(b) Find the Fourier spectrum of the following signal.
12. (a) Where the advantages of using high frequency carrier wave?
(b) What do you mean by synchronies detection?
(c) What are the major advantages of PCM. Justify you answer?
(d) A 1500 KHz carrier frequency is modulated by a 500 Hz audio sine wave.
What is the upper side band?
13. (a) What is the difference between :
(i) a switch and circuit breaker.
(ii) a fuse and circuit breaker?
(b) Discuss the fundamental requirements of protective relay?
(c) Explain the working principle of distance relays.
14. (a) Define information, entropy and information capacity with
appropriate mathematical
expressions.
(b) Draw the block diagram of a typical digital communication system.
Discuss the advantages of
digital communication system over its analogue counterpart.
15. (a) Explain how electricity is generated in a nuclear power plant?
(b) Discuss the different types of unsymmetrical faults
that can occur on a 3φ system. In a 3φ
system, it has been found
that negative sequence Components and zero sequence components
are absent, what do you
conclude from it?
16. Write short notes on any four of the following :
(a) Restriking voltage
(b) Boosters
(c) Electricity tariff
(d) Transient stability
(e) Lighting
(f) BPSK modulation.
=০=
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