46. With the usual notations, a two-port resistive network satisfies the condition A = D =	3	B =	4	C
    	2		3

    
    z₁₁ of the network is
    

1. 1. 	5
      	3

      
      

   
   
   

   2. 	4
      	3

      
      

   
   
   

   3. 	4
      	3

      
      

   
   
   

   4. 	1
      	3

      
      

   
   
   

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1. View Hint View Answer Discuss in Forum

   Z11 =	A	=	4
   	C		4

   
   

   Correct Option: B

   Z11 =	A	=	4
   	C		4

   
   

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47. A two-port network is defined by the relations I₁ = 2V₁ + V₂, I₂ = 2V₁ + 3V₂ Then z₁₂ is
    

1. 1. – 2 Ω

   
   
   

   2. – 1 Ω

   
   
   

   3. -	1	Ω
      	2

      
      

   
   
   

   4. 	1	Ω
      	4

   
   
   

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1. View Hint View Answer Discuss in Forum

   From the equations,
   

   I1 = 2V1 +	(I2 - 2V1)
   	3

   
   

   ⇒ V1 = 3I1 -	I2
   	4

   
   

   ∴ Z12 =	1	Ω
   	4

   
   

   Correct Option: D

   From the equations,
   

   I1 = 2V1 +	(I2 - 2V1)
   	3

   
   

   ⇒ V1 = 3I1 -	I2
   	4

   
   

   ∴ Z12 =	1	Ω
   	4

   
   

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48. 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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1. View Hint View Answer Discuss in Forum

   	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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49. 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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1. View Hint View Answer Discuss in Forum

   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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50. The two electric sub-networks N₁ and N₂ are connected through three resistors as shown in the figure below. The voltage across 5 Ω resistor and 1 Ω resistor are given to be 10V and 5V respectively. Then voltage across 15 Ω resistor is
    

1. 1. – 105 V
      

   
   
   

   2. + 105 V

   
   
   

   3. – 15 V

   
   
   

   4. + 15 V

   
   
   

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1. View Hint View Answer Discuss in Forum

   By KCL, if we take a cutset along all three branches, then total current at the junction is zero.
   i.e. I ₁ + I ₂ + I ₃ = 0
   

   ⇒	10	+ I2 +	5	= 0
   	5		1

   
   ⇒ I₂ = 7A
   and V = – 105 V.

   Correct Option: A

   By KCL, if we take a cutset along all three branches, then total current at the junction is zero.
   i.e. I ₁ + I ₂ + I ₃ = 0
   

   ⇒	10	+ I2 +	5	= 0
   	5		1

   
   ⇒ I₂ = 7A
   and V = – 105 V.

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