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ECE :: Measurements and Instrumentation

  1. The current in a circuit is measured using a 150 : 1 CT If the ammeter reads 0.6 A, the circuit current is

  2. A.
    250 A
    B.
    90 A
    C.
    156 A
    D.
    144 A

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  3. A volt ratio box should have low resistance.

  4. A.
    True
    B.
    False

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  5. A Hall effect transducer has KH = - 1 x 10-8. If B = 1 Wb/m2, I = 3 A and bismuth slab is 2 mm wide, the Hall voltage is

  6. A.
    -7.5 x 10-6 V
    B.
    -15 x 10-6
    C.
    -20 x 10-4 V
    D.
    -22.5 x 10-4 V

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  7. Two ammeters A and B both 0-10 A have internal resistance of 1 Ω and 0.5 Ω respectively. They are connected in parallel. If total current is 15 A, then

  8. A.
    IA = IB = 7.5 A
    B.
    IA = 5 A, IB = 10 A
    C.
    IA = 10 A, IB = 5 A
    D.
    IA = 9 A, IB = 6 A

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  9. Which of the following is not correct?

  10. A.
    Voltmeter should have a very high resistance
    B.
    An ammeter should have a very low resistance
    C.
    A shunt should have a very low resistance
    D.
    An electronic voltmeter draws appreciable current from source

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  11. The loss of charge method can be used to measure

  12. A.
    resistance of shunt
    B.
    insulation resistance of cable
    C.
    resistance of shunt winding
    D.
    both (b) and (c)

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  13. Assertion (A): Maxwell bridge is for measuring inductance of medium magnitude.

    Reason (R): In Maxwell's bridge the unknown inductance is measured by comparing it with a capacitance.

  14. 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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  15. Assertion (A): A semiconductor strain gauge is more accurate than a resistance strain gauge.

    Reason (R): The gauge factor of a semiconductor strain gauge is about 100 where as the gauge factor of a resistance strain gauge is only about 2.

  16. 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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  17. Current density has the dimensions

  18. A.
    IL
    B.
    IL-2
    C.
    IL-3
    D.
    I2L-2

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  19. The resistance of a dc galvanometer is 20 Ω. A current of 10 mA causes full scale deflection. To convert it into 0-300 V voltmeter, we have to use a series resistance of

  20. A.
    30000 Ω
    B.
    29980 Ω
    C.
    6000 Ω
    D.
    15 Ω

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