Practice Test: Question Set - 05
1. The apparent power drawn by an A.C. circuit is 10 kVA and active power is 8 kW. The reactive power in the circuit is
- (A) 4 kVAR
- (B) 6 kVAR
- (C) 8 kVAR
- (D) 16 kVAR
2. In a sine wave the slope is constant
- (A) Between 0° and 90°
- (B) Between 90° and 180°
- (C) Between 180° and 270°
- (D) No where
3. The r.m.s. value of pure cosine function is
- (A) 0.5 of peak value
- (B) 0.707 of peak value
- (C) Same as peak value
- (D) Zero
4. In a pure capacitive circuit if the supply frequency is reduced to 1/2, the current will
- (A) Be reduced by half
- (B) Be doubled
- (C) Be four times at high
- (D) Be reduced to one fourth
5. Capacitors for power factor correction are rated in
- (A) kW
- (B) kVA
- (C) kV
- (D) kVAR
6. The reactance offered by a capacitor to alternating current of frequency 50 Hz is 20 Q. If frequency is increased to 100 Hz, reactance becomes __________ ohms.
- (A) 2.5
- (B) 5
- (C) 10
- (D) 15
7. For the same peak value which of the following wave will 'have the highest r.m.s. value?
- (A) Square wave
- (B) Half wave rectified sine wave
- (C) Triangular wave
- (D) Sine wave
8. The r.m.s. value of a sinusoidal A.C. current is equal to its value at an angle of ________ degrees.
- (A) 90
- (B) 60
- (C) 45
- (D) 30
9. Power factor of an inductive circuit is usually improved by connecting capacitor to it in
- (A) Parallel
- (B) Series
- (C) Either (A) or (B)
- (D) None of the above
10. In the case of an unsymmetrical alternating current the average value must always be taken over
- (A) Unsymmetrical part of the wave form
- (B) The quarter cycle
- (C) The half cycle
- (D) The whole cycle
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