EC
Engineering Classroom
by Himalay Sen

Exams

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Board Questions

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MCQ
2. Out of the following which is not a poor conductor?
Cast iron
Carbon
Copper
Tungsten
ব্যাখ্যা: ব্যাখ্যা: Copper is not a poor conductor. Metals are good conductors of heat and electricity.
4. The electric current is due to the flow of--
positive charges only
negative charges only
both positive and negative charges
neutral particles only
ব্যাখ্যা: ব্যাখ্যাঃ Where there is current, the electrons will Bow in one direction and holes to the other direction. The direction of current flow is defined as the direction of positive charges. But the current flow is the flow of both negative and positive charges.
5. When resistance element of a heater fuses and then we reconnect it after removing a portion of it, the power of the heater will-
decrease
remain constant
increase
none of the above
ব্যাখ্যা: ব্যাখ্যা: When resistance element of a heater fuses and then we reconnected it after removing a portion of it the power of the heater will increases because the resistance of wire decrease due to decrease in length of it.
9. Which of the following material has nearly zero temperature co-efficient of resistance?
Manganin
Carbon
Porcelain
Copper
ব্যাখ্যা: ব্যাখ্যা: Manganin has a low-temperature coefficient of resistance. So it does not change much with temperature.
10. A length of wire has a resistance of 6 ohms. The resistance of a wire of the same material three times as long and twice the cross sectional will be-
36 ohms
9 ohms
1 ohms
12 ohms
12. 'পক প্রণালি' কোন দুটি দেশকে পৃথক করেছে?
ভারত ও পাকিস্তান
মরোক্ক ও স্পেন
ইরান ও ওমান
ভারত ও শ্রীলংকা
ব্যাখ্যা: তথ্য: ভারত শ্রীলংকাকে পৃথক করেছে 'পক প্রণালি'। এটি সংযুক্ত করেছে ভারত মহাসাগর ও আরব সাগরকে।
13. ট্রান্সলে পদ্ধতির রেটিং কত?
11KV
33kV
22kV
66kV
ব্যাখ্যা: ব্যাখ্যা: ট্রান্সলে সিস্টেমে অপারেটিং ভোল্টেজ 33 কেভির উর্ধ্বে ব্যবহার করা
17. An electric fan and a heater are marked as 100W, 220V and 1000W, 220V respectively. The resistance of heater is-
zero
greater than that of fan
less than that of fan
equal to that of fan
18. Which of the following materials has a negative temperature co-efficient of resistance?
Insulator
Conductor
Semiconductor
None of them
ব্যাখ্যা: ব্যাখ্যা: From above options, a semiconductor has the negative temperature co-efficient.