MCQ
1741. The d.c. series motor should never be switched on at no load because-
the field current is zero
the machine does not pickup
the speed becomes dangerously high
it will take too long to accelerate
1742. RMS value of the instantaneous ac voltage V = 300 is-
300x√2
300/√2
300x√3
300/√3
1743. In the maximum value of a current of a circuit is 1 amp (sinusoidal wave). What is the R.M.S. value?
1 Amp
0.637 Amp
0.707 Amp
1.5 Amp
1744. Inductance opposes --in current in a circuit.
only increase
change
only decrease
none of the above
1745. If positive phase sequence of 3-0 load is 'abc', the negative sequence is-
bac
cba
ach
all of the above
1746. Which resistor will be physically larger in size-
10Ω 50W
100Ω 10W
1ΜΩ 1W
1KΩ 1W
1747. What would be the charge of a capacitor 10μF when connected with 20V supply?
200μc
300μc
6200μc
30μc
1748. Inductance opposes --in current in a circuit
only increase
change
only decrease
none of the above
1749. Three equal resistor of 100 is connected in series across a source of Emf 30V. What would be the power consumed by each resistor?
10W
90W
30W
60W
1750. One Horse Power is equal to-
5.50 Foot pound/Second
55.00 Foot pound/Second
550 Foot pound/Second
5500 Foot pound/Second
1751. For an R-L load ---
Active power is greater than apparent power
Reactive power is greater than apparent power
Apparent power is greater than both Active and Reactive power
All are equal
1752. If a phase is multiplied by j, then –
only its magnitude changes
only its direction changes
both magnitude & direction changes.
none of above
1753. Which of the following connections is best suited for 3-phase, 4-wire service?
Δ-Δ
Y-Y
Δ-Υ
Y-A
1754. At parallel resonance-
circuit impedance is minimum
power factor is zero
line current is maximum
power factor is unity
1755. The power factor of an ordinary electric bulb is--
Zero
Unity
Slightly more than zero
Slightly less than unity
1756. If the power factor of a circuit is unity, its reactive power is-
a maximum
zero
quantity
equal to FR
1757. For Y-connection under balanced condition the line to line voltage is-
same as the phase voltage
√3 times the phase voltage
√2 times the phase voltage
none of the above
1758. The power of an AC circuit is given by-
VI cosθ
FZ
VI sinθ
FXL
1759. At parallel resonance the circuit impedance equals to-
L/CR
LC/R
RL/C
CR/L
1760. Which of the following lamp has minimum initial cost of installation but maximum running cost?
incandescent
fluorescent
mercury vapour
sodium vapour