Wednesday, September 9, 2020

Chapter 4: Complex AC Circuits- Page 5

 

Chapter 4: Complex AC Circuits

41. When it is not appropriate to use the formula fr = (1/2π) √LC for a practical parallel LC circuit?
A. when Q of inductor is less than 10
B. when Q of inductor is more than 10
C. when Q of inductor is less than 100
D. none of above


... Answer is (A)

 

 
 

42. In a practical parallel resonant circuit
 

A. IL = Ic
B. IL > Ic
C. IL < Ic
D. IL = 100 Ic

... Answer is (B)

 
 
 

43. In a parallel resonant LC circuit, the line current is

A. much less than IL or Ic
B.
equal to IL or Ic
C. much greater than
IL or Ic
D. none of the above

... Answer is (A)

 

 
 

44. Pure inductive circuit

 
A. takes power from the line during some part of the cycle and then returnsback to it during other part of the cycle
B. consumes some power onaverage
C. does not take power at all from a line
D. none of the above

  ... Answer is (A)

 

 
 
45. Inductance affects the direct current flow
  ...
Answer is (A)

 
 
 

46. Inductance of a coil varies
A.
directly as square of number of turns
B. directly as the permeability of the core

C.
directly as the cross-sectional area of magnetic core
D. All of the above

  ... Answer is (D)

 

 
 

47. All the rules and laws of D.C. circuit also apply to A.C. circuit containing
A.
resistance only
B.
capacitance only
C. inductance only

D. none of the above

... Answer is (A)

 
 

48. Time constant of an inductive circuit

A. increases with decrease of inductance and decrease of resistance
B. increases with decrease of inductance and increase of resistance

C.
increases with increase of inductance and decrease of resistance
D. increases with the increase of inductance and the increase of resistance

... Answer is (C)

 
 

49. 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
 
  ... Answer is (A)

 
 

50.  In a highly capacitive circuit the
A.
reactive power is more than the actual power
B. actual power is more than its reactive power

C. apparent power is equal to the actual power
D. reactive power is more than the apparent power

  ... Answer is (D)

 

 

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