101. An ideal transformer has turns ratio of 2 : 1. Considering high voltage side as port 1 and low voltage side as port 2, then transmission line parameters of transformer will be
     

1. 1. 	0			-2
      	0.5			0

      
      

   
   
   

   2. 	-2			0
      	0			-0.5

      
      

   
   
   

   3. 	2			0
      	0			-0.5

      
      

   
   
   

   4. 	0.5			0
      	0			2

      
      

   
   
   

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   	V1	=	I1	=	N1	=	2
   	V2		I2		N2		1

   
   ⇒ V₁ = 2V₂
   I ₁ = 0.5 I₂
   
   In matrix form,
   
   

   		V1		=		2			0			V2
   		I1				0			-0.5			I2

   
   

   Correct Option: C

   	V1	=	I1	=	N1	=	2
   	V2		I2		N2		1

   
   ⇒ V₁ = 2V₂
   I ₁ = 0.5 I₂
   
   In matrix form,
   
   

   		V1		=		2			0			V2
   		I1				0			-0.5			I2

   
   

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102. In a passive two-port network, the open-circuit impedance matrix is		10			2
     		5			2

     
     If input port is interchanged with the output port, then open-circuit impedance matrix will be
     

1. 1. 	10			2
      	5			2

      
      

   
   
   

   2. 	5			2
      	2			10

      
      

   
   
   

   3. 	5			10
      	2			2

      
      

   
   
   

   4. 	2			5
      	10			2

   
   
   

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   The port-equations are
   V₁ = 10 I ₁ + 2I ₂ ....(i)
   V₂ = 2I ₁ + 5 I₂ ....(ii)
   Rewriting equations (i) and (ii) as
   V₂ = 5 I₂ + 2I₁ ....(iii)
   V₁ = 2 I₂ + 10 I₁ ....(iv)
   Writing in matrix form
   

   
   

   		V2		=		5			2			I2
   		V1				2			10			I1

   
   

   Correct Option: B

   The port-equations are
   V₁ = 10 I ₁ + 2I ₂ ....(i)
   V₂ = 2I ₁ + 5 I₂ ....(ii)
   Rewriting equations (i) and (ii) as
   V₂ = 5 I₂ + 2I₁ ....(iii)
   V₁ = 2 I₂ + 10 I₁ ....(iv)
   Writing in matrix form
   

   
   

   		V2		=		5			2			I2
   		V1				2			10			I1

   
   

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103. The short-circuit test of a 2-port network is shown in Fig.(a) The voltage across the terminals AA' in the network shown in Fig.(b) will be
     
     

1. 1. 20 V
      

   
   
   

   2. 10 V
      

   
   
   

   3. 5 V
      

   
   
   

   4. 2 V

   
   
   

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   Now, in Fig. (b)
   I ₁ = Y₁₁V₁ + Y₁₂. V₂ = 0
   

   ⇒ V1 =	-Y12.V2
   	Y11

   
   

   =	0.1 × 10	= 2 volts
   	0.5

   
   

   Correct Option: D

   
   Now, in Fig. (b)
   I ₁ = Y₁₁V₁ + Y₁₂. V₂ = 0
   

   ⇒ V1 =	-Y12.V2
   	Y11

   
   

   =	0.1 × 10	= 2 volts
   	0.5

   
   

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104. In the circuit shown in the given figure, for R = 20 Ω, the current I is 2 A. When R is 10 Ω, then current I would be
     
     

1. 1. 1 A

   
   
   

   2. 2 A

   
   
   

   3. 2.5 A

   
   
   

   4. 3 A

   
   
   

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   When I = 2 amp, then V_N2 = 20 (4 – I) = 40 volts.
   When R = 10 Ω , then V_N2 remains unchanged.
   

   and I = 4 -		VN2		= 4 - 2 = 2 amp.
   		20

   Correct Option: B

   When I = 2 amp, then V_N2 = 20 (4 – I) = 40 volts.
   When R = 10 Ω , then V_N2 remains unchanged.
   

   and I = 4 -		VN2		= 4 - 2 = 2 amp.
   		20

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105. T-parameters of a 2-port network are [T] =		2			1
     		1			1

     
     If such two 2-port network are cascaded, then z-parameter for the cascaded network is
     

1. 1. 
      

   
   
   

   2. 
      

   
   
   

   3. 
      

   
   
   

   4. 
      

   
   
   

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   [ TN ] =		2			1			2			1		=		5			3
   		1			1			1			1				3			2

   
   V₁ = 5V₂ - 3I₂
   I₁ = 3V₂ - 2I₂
   3V₁ - 5I₁ = I₂
   

   ⇒ V1 =	5	It +	1	I2
   	3		3

   
   

   and V2 =	1	I1 +	2	I2
   	3		3

   Correct Option: C

   [ TN ] =		2			1			2			1		=		5			3
   		1			1			1			1				3			2

   
   V₁ = 5V₂ - 3I₂
   I₁ = 3V₂ - 2I₂
   3V₁ - 5I₁ = I₂
   

   ⇒ V1 =	5	It +	1	I2
   	3		3

   
   

   and V2 =	1	I1 +	2	I2
   	3		3

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