Wednesday, September 9, 2020

Chapter 4: Complex AC Circuits- Page 9

 

Chapter 4: Complex AC Circuits

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


... Answer is (B)

 

 
 

82. The input of an A.C. circuit having power factor of 0.8 lagging is 40kVA. The power drawn by the circuit is
 

A. 32 kW
B. 64 kW
C. 12 kW
D. 22 kW

... Answer is (A)

 
 
 

83. The effective resistance of an iron-cored choke working on ordinary supply frequency is more than its true resistance because of

A. increase in temperature
B. capacitive effect between adjecent coil

C.
iron loss in core
D. skin effect

... Answer is (A)

 

 
 

84. In an A.C. circuit, a low value of KVAR turns compared with kW indicates

 
A. unity power factor
B. maximum load current
C. low efficiency
D. high power factor

  ... Answer is (D)

 

 
 
85. In A.C. circuits, laminated iron is invariable used in order to
  ...
Answer is (C)

 
 
 

86. The ratio of active power to apparent power is known as ..... factor
A.
power
B. form

C. demand
D. load

  ... Answer is (A)

 

 
 

87. All definitions of power factor of a series R-L-C circuit are correct except
A.
ratio of R and Z
B. ratio of W and VA

C.
ratio of net reactance and impedance
D. ratio of KW and KVA

... Answer is (C)

 
 

88. 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. 8 kVAR
B. 16 kVAR

C.
4 kVAR
D. 6 kVAR

... Answer is (D)

 
 

89.  The reactance offered by a capacitor to alternating current of frequency 50 Hz is 20A. If the frequency is increased to 100 Hz, reactance becomes

A. 5
B. 10
C. 15
D. 30 ᘯ
 
  ... Answer is (B)

 
 

90.  What will be the phase angle between two alternating waves of equal frequency, when one wave attains maximum value the other is at zero value?
A.
0°
B. 45°
C. 90°
D. 180°

  ... Answer is (C)

 

 

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