6. The measurement of a quantity

1. 1. is an act of comparison of an unknown quantity with another quantity

   
   
   

   2. is a act of comparison of an unknown quantity with a known quantity whose accuracy may be known or may not be known

   
   
   

   3. is an act of comparison of an unknown quantity with a predefined acceptable standard which is accurately known

   
   
   

   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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7. ‘Creep’ is energy meters can be prevented by

1. 1. using extra turns on the voltage coil

   
   
   

   2. having two holes on opposite sides of the disc

   
   
   

   3. using a stronger brake magnet

   
   
   

   4. using steel laminations of high permeability

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: B

   NA

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8. The sensitivity of an instrument is the

1. 1. smallest increment in the input that can be detected with certainty

   
   
   

   2. largest input change to which the instrument fails to respond

   
   
   

   3. ratio of the change in the magnitude of the output to the corresponding change in the magnitude of the input

   
   
   

   4. closeness of the output values for repeated applications of a constant input

   
   
   

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1. View Hint View Answer Discuss in Forum

   Sensitivity of an instrument is ratio of the change in the magnitude of the output to the corresponding change in the magnitude of the input.

   Correct Option: C

   Sensitivity of an instrument is ratio of the change in the magnitude of the output to the corresponding change in the magnitude of the input.

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9. A 50 Hz voltage is measured with a moving iron voltmeter and a rectifier type ac voltmeter connected in parallel. If the meter readings are V₁ and V₂ respectively and the meters are free from calibration errors, then the form factor of the ac voltage may be estimated as

1. 1. V1

      V2

   
   
   

   2. 1.11V1

      V2

   
   
   

   3. √2V1

      V2

   
   
   

   4. πV1

      V2

   
   
   

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1. View Hint View Answer Discuss in Forum

   Form factor of the wave =	rms Value
   	Mean Value

   
   Moving iron Instrument will show rms value. Rectifier voltmeter is calibrate to read rms value of sinusoidal voltage, i.e. with form factor of 1.11.
   

   ∴ Mean value of the applied voltage =	V2
   	1.11

   
   

   ∴ Form factor =	V1	=	1011V1
   	V2/1.11		V2

   Correct Option: B

   Form factor of the wave =	rms Value
   	Mean Value

   
   Moving iron Instrument will show rms value. Rectifier voltmeter is calibrate to read rms value of sinusoidal voltage, i.e. with form factor of 1.11.
   

   ∴ Mean value of the applied voltage =	V2
   	1.11

   
   

   ∴ Form factor =	V1	=	1011V1
   	V2/1.11		V2

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10. When damping of an instrument is adjusted to enable the pointer to rise quickly to its deflected position without overshooting, in that case the instrument is said to be

1. 1. dead-beat

   
   
   

   2. off-beat

   
   
   

   3. over-damped

   
   
   

   4. under-damped

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: A

   NA

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