A.C. Fundamentals and Circuits Practice Exam - Set 06

Practice Test: Question Set - 06


1. 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

2. A pure inductance connected across 250 V, 50 Hz supply consumes 100 W. This consumption can be attributed to
    (A) The big size of the inductor
    (B) The reactance of the inductor
    (C) The current flowing in the inductor
    (D) The statement given is false

3. In a parallel R-C circuit, the current always _________the applied voltage
    (A) Lags
    (B) Leads
    (C) Remains in phase with
    (D) None of the above

4. In a three-phase supply floating neutral is undesirable because it way give rise to
    (A) High voltage across the load
    (B) Low voltage across the load
    (C) Unequal line voltages across the load
    (D) None of these

5. An A.C. voltage is impressed across a pure resistance of 3.5 ohms in parallel with a pure inductance of impedance of 3.5 ohms,
    (A) The current through the resistance is more
    (B) The current through the resistance is less
    (C) Both resistance and inductance carry equal currents
    (D) None of the above

6. Inductance affects the direct current flow
    (A) Only at the time of turning off
    (B) Only at the time of turning on
    (C) At the time of turning on and off
    (D) At all the time of operation

7. The time constant of the capacitance circuit is defined as the time during which voltage
    (A) Falls to 36.8% of its final steady value
    (B) Rises to 38.6% of its final steady value
    (C) Rises to 63.2% of its final steady value
    (D) None of the above

8. Power factor of electric bulb is
    (A) Zero
    (B) Lagging
    (C) Leading
    (D) Unity

9. If a sinusoidal wave has frequency of 50 Hz with 30 A r.m.s. current which of the following equation represents this wave?
    (A) 42.42 sin 314 t
    (B) 60 sin 25 t
    (C) 30 sin 50 t
    (D) 84.84 sin 25 t

10. Capacitive susceptance is a measure of
    (A) Reactive power in a circuit
    (B) The extent of neutralization of reactive power in a circuit
    (C) A purely capacitive circuit's ability to pass current
    (D) A purely capacitive circuit's ability to resist the flow of current

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