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ECE :: Measurements and Instrumentation

  1. Kelvin's double bridge is used to measure low resistances because

  2. A.
    it has high sensitivity
    B.
    there is no thermoelectric emf
    C.
    resistance variation due to temperature
    D.
    effect of contact and lead resistances is eliminated

  3. Assertion (A): Shunt of an ammeter has a low resistance.

    Reason (R): Shunt may be connected in series or in parallel with ammeter.

  4. 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

  5. The scale of hot wire instrument is linear.

  6. A.
    True
    B.
    False

  7. The D'Arsonval- movement can be converted into audio frequency ac ammeter by adding a

  8. A.
    thermocouple
    B.
    transducer
    C.
    chopper
    D.
    rectifier

  9. The resistance of a 125 Ω strain gauge changes by 1 ohm for 4000 micro strain. The gauge factor is

  10. A.
    1.5
    B.
    2
    C.
    2.5
    D.
    3

  11. Electrostatic voltmeter is suitable only for low voltages.

  12. A.
    True
    B.
    False

  13. An accelerometer has a seismic mass of 0.05 kg and spring constant of 3 x 105 N/m. If maximum displacement of mass is ± 1 mm, the maximum acceleration which can be measured is

  14. A.
    30 m/s2
    B.
    60 m/s2
    C.
    90 m/s2
    D.
    120 m/s2

  15. If an inductance L is connected in one arm of bridge and resistance R1, R2, R3 in other three arms

  16. A.
    the bridge cannot be balanced
    B.
    the bridge can be balanced
    C.
    the bridge is balanced for some specified value of frequency
    D.
    the bridge is balanced for some specific values of R1, R2, R3

  17. A moving iron voltmeter reads 250 V when connected to 250 V dc. If connected to 250 V 50 Hz, the voltmeter reading is likely to be

  18. A.
    250 V
    B.
    252 V
    C.
    248 V
    D.
    210 V

  19. A single element strain gauge bridge has two fixed resistances R1 and R1 of 120 Ω each and a variable resistance which gives full deflection at 120 Ω for zero strain and 120.6 Ω for straine e. If gauge factor is 2, strain e is

  20. A.
    0.0025
    B.
    0.0035
    C.
    0.005
    D.
    0.0075