21. Calculate total current I_T—
    

1. 1. 0·24 ∠ 33°
      

   
   
   

   2. 2·4 ∠ 33°
      

   
   
   

   3. 24 ∠ 30°
      

   
   
   

   4. None of these

   
   
   

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1. View Hint View Answer Discuss in Forum

   The given circuit:
   
   Capacitive reactance,
   

   XC =	1	=	1
   	2πfC		6·28 × 5 × 103 × 0·2 × 10–6

   
   = 159·2Ω
   

   IR =	Vs	=	20	= 0·2A
   	R		100

   
   

   IR =	VS	=	20	= 0·126A
   	XC		159·2

   
   The total current (I_T) in parallel circuit is the vector sum of the branch currents. i.e.
   I_T = I_C.I_R + j I_C = (0·2 + j 0·126)A
   or
   I_T = 0·24 33°

   Correct Option: A

   The given circuit:
   
   Capacitive reactance,
   

   XC =	1	=	1
   	2πfC		6·28 × 5 × 103 × 0·2 × 10–6

   
   = 159·2Ω
   

   IR =	Vs	=	20	= 0·2A
   	R		100

   
   

   IR =	VS	=	20	= 0·126A
   	XC		159·2

   
   The total current (I_T) in parallel circuit is the vector sum of the branch currents. i.e.
   I_T = I_C.I_R + j I_C = (0·2 + j 0·126)A
   or
   I_T = 0·24 33°

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22. The equivalent impedance?
    

1. 1. 15·82 ∠ 20°
      

   
   
   

   2. 25·87 ∠ 20·5°
      

   
   
   

   3. 25·87 – 20·5°
      

   
   
   

   4. None of these

   
   
   

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1. View Hint View Answer Discuss in Forum

   The given circuit:
   
   Z_eq = 10 + 20 || jX_L
   where X_L = 2πf L = 2π × 50 × 0·1 = 31·42Ω
   Now,
   

   Zeq = 10 +	20 × j (31·42)
   	20 + j31·42

   
   = 10 + 16·87 32·48°
   or
   Z_eq = 24·23 × j 9·06
   or
   Z_eq = 25·87 20·5°

   Correct Option: B

   The given circuit:
   
   Z_eq = 10 + 20 || jX_L
   where X_L = 2πf L = 2π × 50 × 0·1 = 31·42Ω
   Now,
   

   Zeq = 10 +	20 × j (31·42)
   	20 + j31·42

   
   = 10 + 16·87 32·48°
   or
   Z_eq = 24·23 × j 9·06
   or
   Z_eq = 25·87 20·5°

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23. Current I?
    

1. 1. 0·77 ∠ – 20·5°
      

   
   
   

   2. 0·77 ∠ 20·5°
      

   
   
   

   3. ∠ 2·77 ∠ 20·5°
      

   
   
   

   4. 1·77 ∠ 20·5°

   
   
   

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1. View Hint View Answer Discuss in Forum

   I =	Vs	=	20
   	Zeq		25·87 20·5°

   
   = 0·77 –20·5°

   Correct Option: A

   I =	Vs	=	20
   	Zeq		25·87 20·5°

   
   = 0·77 –20·5°

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24. The phase angle between voltage and current—
    

1. 1. 20·5°
      

   
   
   

   2. – 20·5°
      

   
   
   

   3. 22·5°
      

   
   
   

   4. None of these

   
   
   

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1. View Hint View Answer Discuss in Forum

   θ = 20·5°
   

   Correct Option: A

   θ = 20·5°
   

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25. The total reactance of a series RLC circuit at resonance—
    

1. 1. equal to X_L
      

   
   
   

   2. equal to X_C
      

   
   
   

   3. equal to R
      

   
   
   

   4. Zero

   
   
   

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1. View Hint View Answer Discuss in Forum

   The total reactance of a series RLC circuit at resonance is zero.

   Correct Option: D

   The total reactance of a series RLC circuit at resonance is zero.

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