120 Important Basic Electrical MCQ Question and Answer | PDF Free Download
1.In a lamp load when more than one lamp are switched on the total resistance of the load
- AIncreases
- BDecreases
- CRemains same
- DNone of the above
2.Resistance of 220 V, 100 W lamp will be
- A4.84 ohm
- B48.4 ohm
- C484 ohm
- D4840 ohm
3.In the case of direct current
- AMagnitude and direction of current remains constant
- BMagnitude and direction of current changes with time
- CMagnitude of current changes with time
- DMagnitude of current remains constant
4.When electric current passes through a bucket full of water, lot of bubbling is observed. This suggests that the type of supply is
- AAC
- BDC
- CAny of above two
- DNone of the above
5.Bulbs in street lighting are all connected in
- AParallel
- BSeries
- CSeries-parallel
- DEnd-to-end
6.Switching of a lamp in house produces noise in the radio. This is because switching operation produces
- AArcing across separating contacts
- BMechanical noise of high intensity
- CBoth mechanical noise and arc between contacts
- DNone of the above
7.Sparking occurs when a load is switched off because the circuit has high
- AResistance
- BInductance
- CCapacitance
- DImpedance
8.Copper wire of certain length and resistance is drawn out to three times its length without change in volume, the new resistance of wire becomes
- A1/9 times
- B3 times
- C9 times
- DUnchanged
9.When resistance element of a heater fuses and then we reconnect it after removing a portion of it, the power of the heater will
- ADecrease
- BIncrease
- CRemain constant
- DNone of the above
10.International ohm is defined in terms of the resistance of
- AA column of mercury
- BA cube of carbon
- CA cube of copper
- DThe unit length of wire
11.Which method can be used for absolute measurement of resistances?
- ALorentz method
- BReleigh method
- COhm?s law method
- DWheatstone bridge method
12.Three 6 ohm resistors are connected to form a triangle. What is the resistance between any two corners?
- A3/2 ohm
- B6 ohm
- C4 ohm
- D8/3 ohm
13.Ohm's law is not applicable to
- ASemi-conductors
- BDC circuit
- CSmall resistors
- DHigh currents
14.Which of the following materials has the least resistivity?
- AZinc
- BLead
- CMercury
- DCopper
15.Which of the following lamps will have least resistance at room temperature?
- A25 W, 220 V
- B100 W, 220 V
- C200 W, 220 V
- D60 W, 220 V
16.When current flows through heater coil it glows but supply wiring does not glow because
- ACurrent through supply line flows at slower speed
- BSupply wiring is covered with insulation layer
- CResistance of heater coil is more than the supply wires
- DSupply wires are made of superior material
17.Which of the following statement is correct?
- AA semi-conductor is a material whose conductivity is same as between that of a conductor and an insulator
- BA semi-conductor is a material which has conductivity having average value of conductivity of metal and insulator
- CA semi-conductor is one which conducts only half of the applied voltage
- DA semi-conductor is a material made of alternate layers of conducting material and insulator
18.An open resistor, when checked with an ohm-meter reads
- AZero
- BInfinite
- CHigh but within tolerance
- DLow but not zero
19._______________ are the materials having electrical conductivity much less than most of the metals but much greater than that of typical insulators.
- AVaristors
- BThermistor
- CSemi-conductor
- DVariable resistors
20.All good conductors have high
- AConductance
- BResistance
- CReluctance
- DThermal conductivity