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.Management Sciences
Category: A.C. Fundamentals, Circuits and Circuit Theory
The transient currents are associated with the____________?
A. changes in the stored energy in the inductors and capacitors
B. impedance of the circuit
C. applied voltage to the circuit
D. resistance of the circuit
If two sinusoids of the same frequency but of different amplitudes and phase angles are subtracted, the resultant is____________?
A. a sinusoid of the same frequency
B. a sinusoid of half the original frequency
C. a sinusoid of double the frequency
D. not a sinusoid
In each of the three coils of a three phase generator, an alternating voltage having an r.m.s. value of 220 V is induced. Which of the following values is indicated by the voltmeters ______?
A. 220 V
B. 220V3V
C. 220/V3 V
D. none of the above
Time constant of an inductive circuit___________?
A. increases with increase of inductance and decrease of resistance
B. increases with the increase of inductance and the increase of resistance
C. increases with decrease of inductance and decrease of resistance
D. increases with decrease of inductance and increase of resistance
For a frequency of 200 Hz, the time period will be__________?
A. 0.05 s
B. 0.005 s
C. 0.0005 s
D. 0.5 s
A heater is rated as 230 V, 10 kW, A.C. The value 230 V refers to__________?
A. average voltage
B. r.m.s. voltage
C. peak voltage
D. none of the above
Power factor of an electrical circuit is equal to____________?
A. R/Z
B. cosine of phase angle difference be-tween current and voltage
C. kW/kVA
D. ratio of useful current to total cur¬rent Iw/I
E. all of these
Inductance of a coil Varies__________?
A. directly as the cross-sectional area of magnetic core
B. directly as square of number of turns
C. directly as the permeability of the core
D. inversely as the length of the iron path
E. as A. to (d)
In a series L-C circuit at the resonant frequency the__________?
A. current is maximum
B. current is minimum
C. impedance is maximum
D. voltage across C is minimum
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