136. The sensitivity of a voltmeter using 0 to 5 mA meter movement is

1. 1. 50 ohm/volt

   
   
   

   2. 100 ohm/volt

   
   
   

   3. 200 ohm/volt

   
   
   

   4. 500 ohm/volt

   
   
   

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1. View Hint View Answer Discuss in Forum

   Sensitivity =	I	=	1	mA = 200 ohm/V
   	IB		5

   Correct Option: C

   Sensitivity =	I	=	1	mA = 200 ohm/V
   	IB		5

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137. While measuring power in three phase load by two wattmeter method, the reading of the two wattmeters will be equal and opposite when

1. 1. power factor is unity

   
   
   

   2. load is balanced

   
   
   

   3. phase angle is between 60° and 90°

   
   
   

   4. the load is purely inductive

   
   
   

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   The wattmeter readings are proportional to cos (30 + θ).
   When θ = 90°, the two quantities are equal and opposite. Therefore, when the load is purely inductive or capacitive, the given situation will occur.
   

   Correct Option: D

   The wattmeter readings are proportional to cos (30 + θ).
   When θ = 90°, the two quantities are equal and opposite. Therefore, when the load is purely inductive or capacitive, the given situation will occur.
   

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138. A compensat ed wattmeter has its reading corrected for error due to the

1. 1. frequency

   
   
   

   2. friction

   
   
   

   3. power consumed in current coil

   
   
   

   4. power consumed in potential coil

   
   
   

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1. View Hint View Answer Discuss in Forum

   A compensated wattmeter has its reading corrected for error due to power consumed in potential coil.

   Correct Option: D

   A compensated wattmeter has its reading corrected for error due to power consumed in potential coil.

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139. The effective reactance of an inductive coil

1. 1. increases because of stray capacitance as the frequency increases

   
   
   

   2. decreases because of stray capacitances as the frequency increases

   
   
   

   3. remain the same irrespective of the increase in frequency even if stray series capacitances are present

   
   
   

   4. none of these

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: B

   NA

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140. A closed coil spring has a stiffness of 20 × 10^-6 N/m. If diameter of the wire is doubled, its outer diameter is made two times and its number of turns are made two times, the stiffness of then new spring will be

1. 1. 20 × 10^-6 N/m

   
   
   

   2. 80 × 10^-6 N/m

   
   
   

   3. 10 × 10^-6 N/m

   
   
   

   4. 160 × 10^-6 N/m

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: A

   NA

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