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ECE :: Measurements and Instrumentation

  1. An oscilloscope has an input impedance consisting of 1 MΩ and 20 pF is parallel. A high impedance probe connected to input of this oscilloscope has a 10 MΩ series resistance. This 10 MΩ series resistance

  2. A.
    may not be shunted
    B.
    should be shunted by 2 pF capacitor
    C.
    should be shunted by 20 pF capacitor
    D.
    should be shunted by 200 pF capacitor

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  3. Which of the following is used as detector in audio frequency ac bridges?

  4. A.
    AC voltmeter
    B.
    CRO
    C.
    Head phones
    D.
    Vibration galvanometer

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  5. Assertion (A): The gall tinsley potentiometer is a coordinate potentiometer and has two exactly similar potentiometers.

    Reason (R): An ac potentiometer may measure the unknown voltage in polar form or rectangular coordinate form.

  6. A.
    Both A and R are true and R is correct explanation of A
    B.
    Both A and R are true but R is not correct explanation of A
    C.
    A is true R is false
    D.
    A is false R is true

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  7. If d1, d2, ..., dn are n individual deviations, the standard deviation is

  8. A.
    B.
    C.
    D.
    none of the above

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  9. DC voltage of the order of a few mV can be accurately of measured by

  10. A.
    PMMC voltmeters
    B.
    moving iron voltmeter
    C.
    null balancing potentiometer
    D.
    electrostatic voltmeter

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  11. If the load current is high, the pressure coil of wattmeter should be connected directly across the load.

  12. A.
    True
    B.
    False

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  13. In measurements using CRO, Lissajous patterns are used to

  14. A.
    measure magnitude of peak voltage
    B.
    measure frequency
    C.
    measure impedance
    D.
    measure current

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  15. A dynamometer wattmeter is suitable for both dc and ac.

  16. A.
    True
    B.
    False

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  17. If Ey is the voltage applied to Y plates, the vertical deflection of beam is proportional to

  18. A.
    Ey
    B.
    Ey
    C.
    Ey1.5
    D.
    Ey2

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  19. The method of frequency compensation in moving iron voltmeter is

  20. A.
    to use a capacitor in series with coil
    B.
    to connect a capacitor in parallel with coil
    C.
    to connect a capacitor in parallel with series resistance
    D.
    none of the above

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