176. A-TEM wave incident normally upon a perfect conductor the E and H fields at the boundary will be respectively—

1. 1. Minimum and minimum

   
   
   

   2. Maximum and maximum

   
   
   

   3. Minimum and maximum

   
   
   

   4. Maximum and minimum

   
   
   

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1. View Hint View Answer Discuss in Forum

   At boundary the fields are in phase opposition 180º out of phase and whole energy is reflected back for perfect conductor. Hence E and H fields at the boundary will be maximum and minimum respectively.

   Correct Option: D

   At boundary the fields are in phase opposition 180º out of phase and whole energy is reflected back for perfect conductor. Hence E and H fields at the boundary will be maximum and minimum respectively.

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177. The magnitude of open circuit and short circuit input impedances of a transmission line are 100 Ω and 25 Ω respectively the characteristic impedance of the line is—

1. 1. 25 Ω

   
   
   

   2. 50 Ω

   
   
   

   3. 75 Ω

   
   
   

   4. 100 Ω

   
   
   

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1. View Hint View Answer Discuss in Forum

   Characteristic impedance is given in terms of short circuit and open circuit impedance Z_c =√Z_SCZ_OC = √25 × 100 = √2500 = 50Ω

   Correct Option: B

   Characteristic impedance is given in terms of short circuit and open circuit impedance Z_c =√Z_SCZ_OC = √25 × 100 = √2500 = 50Ω

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178. Find Q of the coil at resonance having frequency 1 MHz—
     

1. 1. 103

      ∏

   
   
   

   2. 10³

   
   
   

   3. 104

      ∏

   
   
   

   4. None of these

   
   
   

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1. View Hint View Answer Discuss in Forum

   At resonance X_L = X_C
   

   jωL =	1
   	jωC

   
   or
   

   L =	1	=	1
   	ω20C		(2∏ × 106)2 × 50 × 10−12

   
   

   =	1
   	50 × 4∏2

   Q =	ω20L	=	106 × 2∏	×	1
   	R		10		50 × 4∏2

   
   

   =	103
   	∏

   Correct Option: A

   At resonance X_L = X_C
   

   jωL =	1
   	jωC

   
   or
   

   L =	1	=	1
   	ω20C		(2∏ × 106)2 × 50 × 10−12

   
   

   =	1
   	50 × 4∏2

   Q =	ω20L	=	106 × 2∏	×	1
   	R		10		50 × 4∏2

   
   

   =	103
   	∏

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179. Consider the following statements: For electromagnetic waves propagating in free space:
     1. Electric field is perpendicular to direction of propagation.
     2. Electric field is along the direction of propagation.
     3. Magnetic field is perpendicular to direction of propagation.
     4. Magnetic field is along the direction of propagation.
     Which of these statements are correct?

1. 1. 1 and 3

   
   
   

   2. 1 and 4

   
   
   

   3. 2 and 3

   
   
   

   4. 2 and 4

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: A

   NA

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180. The circulation of ^→H around the closed contour C, shown in the figure is—
     

1. 1. 0

   
   
   

   2. 2 I

   
   
   

   3. 4 I

   
   
   

   4. 6 I

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: C

   NA

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