MCQ
6441. At parallel resonance the circuit impedance equals to-
L/CR
LC/R
RL/C
CR/L
6442. Inductance opposes --in current in a circuit
only increase
change
only decrease
none of the above
6443. The power factor of an ordinary electric bulb is--
Zero
Unity
Slightly more than zero
Slightly less than unity
6444. 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
6445. Four capacitors each of 40µF are connected in parallel, the equivalent capacitance will be-
160µF
40µF
10µF
5µF
6446. 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
6447. 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
6448. The capacitive reactance of a circuit is-frequency.
independent of
inversely proportional to
directly proportional to
none of the above
6449. What is the peak-to-peak value for 120V ac?
240V
339V
480V
391V
6450. In a series R.L circuit, voltage across resistor inductor are 3V and 4V respectively, then what is the applied voltage?
7V
4V
5V
3V
6451. The unit of inductance—
Inducta
henry
inductive reactance
ohm
6452. The average value of a sinusoidal current is 100A. Its rms value is-
70.7A
63.7A
141.4A
111A
6453. Which of the following connections is best suited for 3-phase, 4-wire service?
Δ-Δ
Y-Y
Δ-Υ
Y-A
6454. Inductance opposes --in current in a circuit.
only increase
change
only decrease
none of the above
6455. If a phase is multiplied by j, then –
only its magnitude changes
only its direction changes
both magnitude & direction changes.
none of above
6456. One Horse Power is equal to-
5.50 Foot pound/Second
55.00 Foot pound/Second
550 Foot pound/Second
5500 Foot pound/Second
6457. RMS value of the instantaneous ac voltage V = 300 is-
300x√2
300/√2
300x√3
300/√3
6458. Which of the following lamp has minimum initial cost of installation but maximum running cost?
incandescent
fluorescent
mercury vapour
sodium vapour
6459. The phase sequence of a three-phase system is RYB. The other possible phase sequence can be-
BRY
YRB
RBY
none of the above
6460. At parallel resonance-
circuit impedance is minimum
power factor is zero
line current is maximum
power factor is unity