Polytechnic 2nd Semester suggestion | WB Polytechnic 2nd Semester suggestion
সমস্ত পলিটেকনিক সেকেন্ড সেমিস্টারের ছাত্র ছাত্রীদের জন্য এই সাজেশন গুলি খুবই গুরুত্বপূর্ণ হতে চলেছে . বিশেষ করে এই বিষয়টি যেহেতু এই প্রথম সেকেন্ড সেমিস্টারের ছাত্র ছাত্রীরা পরীক্ষা দিতে চলেছে সেই ক্ষেত্রে প্রতি বছর থেকে নেওয়া বিশেষ প্রশ্ন-উত্তর এইখানে দেওয়া রয়েছে এতে ছাত্র-ছাত্রীদের বিশেষ সুবিধা হবে।
Unit - 1 Introduction
MULTIPLE CHOICE-TYPE QUESTIONS (MCQ) & ANSWERS :
1. Which of the following statements is correct regarding resistance
(a) The resistance of a conductor is the property by which the conductor oppose the flow of current through it
. (b) The resistance of a conductor is independent of the temperature.
(c) The resistance of a conductor does not depend upon material of the conductor.
(d) none of these.
2. Two donductor A & B of same material and length l and 2l have radius r and 2r respectively. Find the ratio of their specific resistance—
(a) 1:2;
(b) 1:1;
(C) 1:4;
(d) none of these.
3. A circuit component that oppose the change in circuit voltage is-
(a) resistance ;
(b) inductance ;
(c) capacitance ;
(d) none of these.
4. Ideal voltage source should have—
(a) zero internal resistance ;
(b) infinite internal resistance;
(c) large value of emf;
(d) none of these.
5. A practical current source is represented by-
(a) a resistance in series with an ideal current source ;
(b) a resistance in parallel with an ideal current source ;
(c) both of (a) & (b);
(d) none of these.
6. Which of the following is a passive component-
(a) inductor ;
(b) voltage source ;
(c) transistor ;
(d) none of these.
Ans. 1.(a) ; 2(b); 3(c); 4(i); 5(b) ; 6(a).
LONG ANSWER-TYPE QUESTIONS :
1. Write the differences between periodic and non-periodic waveforms.
2. Explain ideal voltage source.
3. Write about independent voltage source.
4. Explain practical current source.
5. How voltage source transforin into current source.
Unit - 2 Electric Magnetic Simple Problems
Unit - 3 Ac Circuit Mcq
MULTIPLE CHOICE-TYPE QUESTIONS (MCQ) AND ANSWERS Choose the right one from the given alternatives against each question.
1. The form factor for a sinusoidal a.c voltage is—
(i) 1:41 ; (ii) 1.11 ; (iii) 1.00 ; (iv) 0.707
2. The frequency of an a.c voltage is given by ; e = 100 cos wt is—
(i) 50 Hz; (ii) 314 Hz; (iii) 60 Hz; (iv) 25 Hz
3. In an a.c system the ratio of the maximum current to average current is called—
(i) form factor; (ii) peak factor; (iii) load factor; (iv) power factor
4. In a series R-L circuit, the applied voltage
(i) lags the current ; (ii) leads the current ; (iii) in phase with the current ; (iv) 90° ahead of the current
5. Amplitude factor for a sinusoidal a.c voltage is—
(i) 1:11; (ii) 0.707 ; (iii) 1:414
6. An ac voltage is given by 100 sin 314 t. The frequency of the voltage is—
(i) 60 Hz; (ii) 50 Hz; (iii) 25 Hz
7. In a circuit containing R, L and C, power loss takes place is
(i) L only; (ii) C only ; (iii) R only ; (iv) all of R, L, C
8. Power factor of an incandescent lamp is—
(i) lagging ; (ii) unity; (iii) leading ; (iv) zero
9. Capacitive reactance is more when
(i) Capacitance is more and freq. of supply is less ;
(ii) Capacitance is less and freq. of supply is more. ;
(iii) Capacitance is more and freq.
of supply is more. ;
(iv) Capacitance is less and freq. of supply is less.
10. Capacitors for p.f correction are rated in—
(i) kw ; (ii) KVA ; (iii) KVAR ; (iv) KV
11. When the supply frequency is increased the resistance of are inductor will—
(i) increase ; (ii) decrease ; (iii) remains the same ; (iv) can not be predicted
12. In a R-C circuit the current-
(i) leads the voltage ; (ii) lags the voltage ; (iii) is in phase with the voltage ; (iv) either (b) or (c).
13. The maximum value of sinewave current is 100 amps, the r.m.s value of current is the circuit will be
(i) 7:07 amps ; (ii) 66-37 amps ; (iii) 70-72 amps ; (iv) 90 amps
14. The power factor of a circuit is 0.9, the Q factor will—
(i) 0:111; (ii) 1 ; (iii) 0.81 ; (iv) 1.111.
15. The voltage of a 100ow heater is reduced to half, the output will reduced to
(i) 500w; (ii) 250w ; (iii) 125w ; (iv) remain unaltered
16. In a series R-L circuit, the applied voltage—
(i) lags the current ; (ii) leads the current ; (iii) in phase with the voltage ; (iv) lags by 90°
17. In ac system. we generate sinewave form because-
(i) It can easily be drawn ; (ii) It produces least disturbance in electric circuit ; (iii) It is nature's standard ; (iv) Other waveforms cannot be produced casily.
Unit - 4 Transformer and Machine
Long Answer Type-Questions :
1. Describes the principle of operating of a transformer.
2. What are the different parts of a transformer. State the function of transformer.
3. What is transformation ratio?
4 What are the different type of transformer.
5. What are the different types of losses in transform. 6. What is DC generator? Describe the principle of operation of it?
7. What are the main part of a DC machine?
8. What are the different type of DC generation?
9. 'Explain the principle of DC motor.
10. What are the different type of DC motor?
11. State the working principle of 3ph. Induction motor.
12. What are the different parts of induction motor.
13. What is slip and sychronons speed.
14. What are the types of induction speed.
15. Describe the principle of working of a 1-Ph induction motor.
16. Why startor is used? Name different types of starter used in DC motor starting.
17. What are the different types of starter used to start induction motor.
18. Write application of series and shunt DC motor.
19. Write application of 3-Ph induction motor.
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