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MCQ
1. The number of electron in the outermost orbit of carbon atom is-
8
2
4
6
2. The electric current is due to the flow of--
positive charges only
negative charges only
both positive and negative charges
neutral particles only
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.
3. A 15 V source is connected across a 12 resistor. How much energy is used in three minutes?
938Wh
56.25Wh A
0.938Wh
5.6Wh
4. Which of the following material has nearly zero temperature co-efficient of resistance?
Manganin
Carbon
Porcelain
Copper
ব্যাখ্যা: Manganin has a low-temperature coefficient of resistance. So it does not change much with temperature.
5. How many watt-hours represent 65 W used for 18h?
11.7Wh
11,700Wh
1.170Wh
117,000Wh
6. 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: 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.
7. 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
8. Which of the following materials has a negative temperature co-efficient of resistance?
Insulator
Conductor
Semiconductor
None of them
ব্যাখ্যা: From above options, a semiconductor has the negative temperature co-efficient.
9. Ampere second could be the unit of-
Power
Energy
Conductance
Charge
10. It becomes more difficult to remove-
any electron from the orbit
first electron from the orbit
second electron from the orbit
third electron from the orbit
11. What is the unit of work?
Newton
Watt
Joule
Pascal
12. One Newton meter is same as-
one watt
five joules
one joule
one joule second
13. 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
14. Out of the following which is not a poor conductor?
Cast iron
Carbon
Copper
Tungsten
ব্যাখ্যা: Copper is not a poor conductor. Metals are good conductors of heat and electricity.
15. Relative permeability of vacuum is-
4π10^-7 H/m
1H/m
1/4π
1
16. Which is the lightest particle of an atom?
Neutron
Proton
Electron
All have same weight
17. A 1k, 1W resistor can safely pass a current of-
31.62mA
100mA
150 mA
500 mA
18. The unit of absolute permitivity of a medium is-
joule/coulomb
Newton meter
farad/meter
farad/coulomb
19. The basic unit of electric charge is-
Ampere-hour
Joule
Coulomb
Newton
20. একটি ওয়াটমিটার নিম্নের কোন মানটি দেখায়?
অ্যাপারেন্ট পাওয়ার
অ্যাকটিভ পাওয়ার
রিয়্যাকটিভ পাওয়ার
কে.ভি.এ. মান