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ECE :: Measurements and Instrumentation

  1. In a moving coil instrument, the deflecting torque is proportional to

  2. A.

     Current

    B.

     Square of the current

    C.

     Squareroot of the current

    D.

     Sine of the measurand

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  3. In a moving iron meter, the deflecting torque is proportional to

  4. A.

     Current through the coil

    B.

     Square of the current through the coil

    C.

     Sine of the measurand

    D.

     Squareroot of the measurand

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  5. Which wave has the least form factor?

  6. A.

     Square wave

    B.

     Rectangular wave

    C.

     Sine wave

    D.

     Triangular wave

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  7. The current coil of a wattmeter is connected to the CT of R-phase. The potential coil is connected across Y and B phases. The wattmeter measures

  8. A.

     Active power in R phase

    B.

     Active power of Y phase

    C.

     Reactive power of R phase

    D.

     Power proportional to 3 phase power if the load is balanced

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  9. Two voltmeters have the same range 0-400V. The internal impedance are 30,000 Ohms and 20,000 Ohms. If they are connected in series and 600V be applied across them, the readings are

  10. A.

     360V and 240V

    B.

     300V each

    C.

     400V and 200V

    D.

     One of the meters out of the range and other 100V

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  11. The two pressure coils of a single phase power factor meter have

  12. A.

     The same dimensions and the same number of turns

    B.

     The same dimension but different number of turns

    C.

     The same number of turns but different dimensions

    D.

     None of the above

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  13. To measure the flux, devices used are based on

  14. A.

     Voltaic effect

    B.

     Piezo-electric effect

    C.

     Hall effect

    D.

     Photo-voltaic effect

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  15. No eddy current and hysteresis losses occur in

  16. A.

     Electrostatic instruments

    B.

     PMMC instruments

    C.

     Moving iron instruments

    D.

     Electrodynamo meter instruments

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  17. The absolute measurement of resistance is done by

  18. A.

     Ohm’s law method

    B.

     Bridge Method

    C.

     Rayleigh method

    D.

     Lorenz method

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  19. For power measurement of three phase circuit by two wattmeter method, when the value of power factor is less than 0.5 lagging

  20. A.

     One of the wattmeters will read zero

    B.

     Both give the same readings

    C.

     One of the wattmeter connections will have to be reversed

    D.

     Pressure coil of the wattmeter will become ineffective.

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