Wednesday, September 9, 2020

Chapter 4: Complex AC Circuits- Page 8

 

Chapter 4: Complex AC Circuits

71. Time constant of a Capacitive circuit
A. increases with the increase of capacitance and decrease of resistance
B. increase with increase of capacitance and increase of resistance
C. increases with the decrease of capacitance and decrease of resistance
D. increases with thedecrease of capacitance and increase of resistance


... Answer is (B)

 

 
 

72. Magnitude of current at resonance in R-L-C circuit
 

A. depends upon the magnitude of C
B. depends upon the magnitude of R, L and C
C. depends upon the magnitude of R
D. depends upon the magnitude of L

... Answer is (C)

 
 
 

73. Power factor of magnetising component of current of a transformer is

A. 0.8 lag
B. 0.8 lead
C. zero
D. unity

... Answer is (C)

 

 
 

74. In a R-L-C circuit

 
A. exchange of power takes place between capacitor and supply line
B. power is consumed in resistance and is equal to I²R
C. exchange of power takes place between inductor and supply line
D. All of the above

  ... Answer is (B)

 

 
 
75. In R-L-C series resonant circuit magnitude of resonance frequency can be changed by changing the value of
  ...
Answer is (D)

 
 
 

76. In a series L-C circuit at the resonant frequency the
A.
impedance is maximum
B. voltage across C is minimum

C. current is maximum
D. current is minimum

  ... Answer is (C)

 

 
 

77. The time constant of a series R-C circuit is given by
A.
R/C
B. RC²
C. RC
D. R
²C

... Answer is (C)

 
 

78. If resistance is 20Ω and inductance is 2H in a R-L series circuit, then time constant of this circuit will be

A. 100 s
B. 10 s
C. 0.1 s
D. 0.01 s

... Answer is (C)

 
 

79.  Which of the following coil will have large resonant frequency?

A. A coil with large distributed capacitance
B. A coil with low distributed capacitance
C. A coil with large resistance
D. A coil with low resistance
 
  ... Answer is (A)

 
 

80.  The safest value of current the human body can carry for more than 3 second is
A.
15 mA
B. 25 mA
C. 4 mA
D. 9 mA

  ... Answer is (D)

 

 

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