EC
Engineering Classroom
by Himalay Sen

Exams

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Board Questions

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MCQ
21. Which quantity consists of a unit 1 kWh?
energy
power
time
charge
ব্যাখ্যা: ব্যাখ্যা: 1 kWh is the amount of energy used by a 1 kW (1000 watt) resistance for 1 hour. Energy = Power x Time
25. Resistance of a conductor of diameter and length L is R ohm. It the diameter of the conductor is halved and its length is doubled the resistance will be-.
2R ohm
4R ohm
8R ohm
3R ohm
26. Semiconductor-এর temperature coefficient of resistance--
Negative
Zero
Positive
কোনোটিই নয়
ব্যাখ্যা: ব্যাখ্যা: Semiconductor-এর temperature coefficient of resistance Negative
32. Which of the following quantites consist of unit as WATT?
force
charge
current
power
ব্যাখ্যা: ব্যাখ্যা: The St unit of power is the watt and it is discover by the Scottish Engineer James Watt. Power is the rate of consumption of electric energy. So, it is equivalent joules per second.
37. Unit of magnetic flux density-
tesla
lux
weber
henry
ব্যাখ্যা: ব্যাখ্যা: Magnetic Flux density has the dimension mas per time squared electric current. The St derived unit of magnetic flux density is the tesla.
38. The minimum dielectric stress in a cable is at-
conductor
surface centre of conductor
lead sheath
none of the above
ব্যাখ্যা: ব্যাখ্যা: Equation of Resistivity of a wire is- So, resistivity of wire is directly proportional to cross section area (A) and inversly proportional to length (L) of wire.
40. The resistivity of the conductor depends on-
area of the conductor
length of the conductor
type of material
none
ব্যাখ্যা: ব্যাখ্যা: Resistivity depends upon nature of material and physical conditions.