201. 160. Match the following:
     (A) ∇ × H = J
     (B) ƒOs E·dl = –d/dt ƒs B·ds
     (C) ∇ · J = –δρ/∇t
     1. Continuity equation
     2. Faraday's law
     3. Ampere's law
     4. Gauss's law
     5. Biot-Savart law

1. 1. A - 1, B - 2, C - 3

   
   
   

   2. A - 4, B - 1, C - 5

   
   
   

   3. A - 3, B - 5, C - 4

   
   
   

   4. A - 2, B - 4, C - 1

   
   
   

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   NA

   Correct Option: D

   NA

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202. For a dipole antenna—

1. 1. The radiation intensity is maximum along the normal to the dipole axis

   
   
   

   2. The current distribution along its length is uniform irrespective of the length

   
   
   

   3. The effective length equals to its physical length

   
   
   

   4. The input impedance is independent of the location of the feed-point

   
   
   

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   In a dipole antenna radiation is almost nil along its axis and maximum in a direction perpendicular to its axis.

   Correct Option: A

   In a dipole antenna radiation is almost nil along its axis and maximum in a direction perpendicular to its axis.

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203. A plane electromagnetic wave travelling along +z-direction, has its electric field given by E_x = 2 cos (t) and E_y = 2 cos (t + 90) the wave is—

1. 1. Linearly polarised

   
   
   

   2. Right circularly polarised

   
   
   

   3. Left circularly polarised

   
   
   

   4. Elliptically polarised

   
   
   

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   E_x = 2 cos ωt,
   E_y = 2 cos (ωt + 90º)
   = – 2 sin ωt
   E_y/ E_x = – tan ωt
   This is a left circularly polarized wave.

   Correct Option: C

   E_x = 2 cos ωt,
   E_y = 2 cos (ωt + 90º)
   = – 2 sin ωt
   E_y/ E_x = – tan ωt
   This is a left circularly polarized wave.

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204. Consider a transmission line of characteristics impedance 50 ohm. Let it be terminated at one end by + j 50 ohm. The VSWR produced by it in the transmission line will be—

1. 1. + 1

   
   
   

   2. 0

   
   
   

   3. ∞

   
   
   

   4. + j

   
   
   

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   Reflection coefficient is given by
   

   ρ =		ZL − Z0	=	j 50 − 50
   		ZL + Z0		j 50 + 50

   
   Hence    |ρ| =
   √(50² + 50²)/ √(50² + 50²)
   

   and the VSWR =	1 + |ρ|	=	2	= ∞
   	1 − |ρ|		0

   Correct Option: C

   Reflection coefficient is given by
   

   ρ =		ZL − Z0	=	j 50 − 50
   		ZL + Z0		j 50 + 50

   
   Hence    |ρ| =
   √(50² + 50²)/ √(50² + 50²)
   

   and the VSWR =	1 + |ρ|	=	2	= ∞
   	1 − |ρ|		0

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205. A transmission line whose characteristic impedance is a pure resistance—

1. 1. Must be a lossless line

   
   
   

   2. Must be a distortionless line

   
   
   

   3. May not be a lossless line

   
   
   

   4. May not be a distortionless line
      

   
   
   

   5. (C) & (D)

   
   
   

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   We know that,
   

   Z0 =	√	R + jωL
   		G + jωC

   
   With Z₀ as pure resistance, we have
   Z₀ = R + j₀
   1. Lossless line has: R = G = 0;
   ∴ Z₀ = √L/C
   2. Distortionless line: R/ G = L/C
   3. L = 0, C = 0,   Z = √R/G Thus transmission line may be lossless, distortionless or with L = C = 0.

   Correct Option: E

   We know that,
   

   Z0 =	√	R + jωL
   		G + jωC

   
   With Z₀ as pure resistance, we have
   Z₀ = R + j₀
   1. Lossless line has: R = G = 0;
   ∴ Z₀ = √L/C
   2. Distortionless line: R/ G = L/C
   3. L = 0, C = 0,   Z = √R/G Thus transmission line may be lossless, distortionless or with L = C = 0.

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