86. Which one of the following types of indicating instruments is an electrometer?
    

1. 1. Electrodynamometer

   
   
   

   2. PMMC

   
   
   

   3. Electrostatic

   
   
   

   4. Moving iron

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: C

   NA

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87. Which one of the following types of indicating instruments is an electrometer?
    

1. 1. Electrodynamometer

   
   
   

   2. PMMC

   
   
   

   3. Electrostatic

   
   
   

   4. Moving iron

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: C

   NA

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88. The sensitivity of thermostats as compared with sensitivity of platinum resistance temperature detector over a temperature range of– 100° to 400°C to change in temperature is

1. 1. 100 times

   
   
   

   2. 10_{6 times}

   
   
   

   3. 10⁷ times

   
   
   

   4. 10³ times

   
   
   

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   NA

   Correct Option: B

   NA

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89. A thermistor exhibits

1. 1. only a negative change of resistance with increase in temperature

   
   
   

   2. only a positive change of resistance with increases in temperature

   
   
   

   3. can exhibit either a negative or positive change of resistance with increase of temperature depending upon the type of material

   
   
   

   4. none of these

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: C

   NA

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90. A 35 V d.c. supply is connected across a combined resistance of 600 ohms and an unknown resistance of R ohms in series. A voltmeter having a resistance of 1.2 kW is connected across 600 ohm resistor and reads 5 V. The resistance R will be
    

1. 1. 120 ohms

   
   
   

   2. 500 ohms

   
   
   

   3. 1.7 k ohms

   
   
   

   4. 2.4 k ohms

   
   
   

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   Parallel sum of 600 ohm and 1200 ohm
   

   =	600 × 1200	= 400 ohm
   	1800

   
   

   ∴	R	=	400
   	35.5		5

   
   or R = 2400 ohms = 2.4 k ohms

   Correct Option: D

   Parallel sum of 600 ohm and 1200 ohm
   

   =	600 × 1200	= 400 ohm
   	1800

   
   

   ∴	R	=	400
   	35.5		5

   
   or R = 2400 ohms = 2.4 k ohms

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