Eddy Current Practise

92 Questions | Total Attempts: 1281

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Software Testing Quizzes & Trivia

Theory and application of non destructive testing method eddy current


Questions and Answers
  • 1. 
    A method of minimizing the effect of indications caused by gradual dimensional changes whileretaining the indications caused by discontinuities is to:
    • A. 

      Include a high pass filter in the eddy current test equipment

    • B. 

      Include a low pass filter in the eddy current test equipment

    • C. 

      Increase the band pass of the amplifier

    • D. 

      Use the impedance method of testing

  • 2. 
    Which of the following methods may be used to improve the signal-to-noise ratio of an eddycurrent test system?
    • A. 

      Filtering or differentiation

    • B. 

      Phase discrimination

    • C. 

      Intergration

    • D. 

      All 3 are correct

  • 3. 
    In order to decrease the effect on conductivity readings due to variations in test part thickness:
    • A. 

      The test frequency should be increased

    • B. 

      The test frequency should be decreased

    • C. 

      The fill factor should be decreased

    • D. 

      There is no practical method for decreasing this effect

  • 4. 
    When testing by the eddy current method, discontinuities will be most easily detected when the eddy currents are:
    • A. 

      Coplanar with the major plane of the discontinuity

    • B. 

      Perpendicular to the major plane of the discontinuity

    • C. 

      Parallel to the major plane of the discontinuity

    • D. 

      90 degress out of the phase with current in the coil

  • 5. 
     A term used to describe the effect observed due to a change in the electromagnetic coupling between a test specimen and a probe coil when the distance of separation between themis varied is:
    • A. 

      Fill factor

    • B. 

      Edge effect

    • C. 

      End effect

    • D. 

      Lift off

  • 6. 
    A term to define the phenomenon where, at very high frequencies, the eddy current flow is resrticted to an extremely thin outer layer of the conductor is:
    • A. 

      Skin effect

    • B. 

      High frequency filtration

    • C. 

      Low frequency filtration

    • D. 

      Any of these answers

  • 7. 
    The fill factor when a 1/2 inch diameter bar is inserted in a 1 inch diameter coil is:
    • A. 

      0.5 (50%)

    • B. 

      0.75 (75%)

    • C. 

      1.0 (100%)

    • D. 

      0.25 (25%)

  • 8. 
    The term used to define the difference between actual instrument output and expectedoutput as defined by a straight line calibration curve is:
    • A. 

      Phase shift

    • B. 

      Nonlinearity

    • C. 

      Lift off

    • D. 

      Skin effect

  • 9. 
    Which of the following could be used to suppress unwanted high frequency harmonics?
    • A. 

      Low pass filter

    • B. 

      Oscillator

    • C. 

      Phase discriminator

    • D. 

      High pass filter

  • 10. 
    The impedance change of an eddy current test coil due to a change in the test partcharacteristics can be most easily analyzed as a combined change in:
    • A. 

      Capacitive reactance and resistance

    • B. 

      Harmonic frequencies and inductive reactance

    • C. 

      Signal ampllitude and phase

    • D. 

      Retentivity harmonic frequencies

  • 11. 
    The inductive reactance of a test coil can be calculated using the formula:
    • A. 

      Xr = 2 pie L

    • B. 

      Xr = 1/2 pie L

    • C. 

      Xr = 2 pie fL

    • D. 

      Xr = 1R

  • 12. 
     When conducting an eddy current test, variations in the test material can be detectedas variations in:
    • A. 

      Test speed

    • B. 

      Impedance of the pickup coil

    • C. 

      None of the 2 answers

    • D. 

      Both answers are correct

  • 13. 
    A term used to define 2 or more coils electrically connected in opposition such that any electromagentic condition which is not common to both a test specimen and areference specimen will produce an unbalance in the system is:
    • A. 

      Differential

    • B. 

      Absolute

    • C. 

      Laminar

    • D. 

      Flying probes

  • 14. 
    Tubing is generally inspected using:
    • A. 

      U-Shaped coils

    • B. 

      Gap coils

    • C. 

      Encircling coils

    • D. 

      None of the answers

  • 15. 
    When testing small parts in an eddy current encircling coil for permeability measurements,which of the following test parameters may be considered important?
    • A. 

      Length of the test sample

    • B. 

      Thickness of the test sample

    • C. 

      Cross-sectional area of the test sample

    • D. 

      AllĀ  answers are correct

  • 16. 
    In a test coil consisting of both a primary and secondary winding, the voltage across thesecondary is a function of:
    • A. 

      Test material permeability

    • B. 

      Test frequency

    • C. 

      Geometry of the test object

    • D. 

      All answers are correct

  • 17. 
    Eddy current testing relies on the principle of:
    • A. 

      Magnetostriction

    • B. 

      Electromagnetic induction

    • C. 

      Piezoelectric energy conversion

    • D. 

      Magnetomotive force

  • 18. 
    When the H field strength around a material is increased and then decreased to zero,the induction field B within the part does not return to zero, the term to define this Bvalue when H has returned to zero is:
    • A. 

      Coercive force

    • B. 

      Residual Magnetism

    • C. 

      Saturation value

    • D. 

      Hysteresis loss

  • 19. 
    The term used to define the value of H field required to decrease the remanence of a material to zero is:
    • A. 

      Coercive force

    • B. 

      Magnetizing force

    • C. 

      Back emf

    • D. 

      The overlap value

  • 20. 
    The 3 major specimen parameters which influence eddy current testing are:
    • A. 

      Electrical conductivity, frequency, and material geometry

    • B. 

      Density, permeability, and frequency

    • C. 

      Electrical conductivity, permeability, and material geometry

    • D. 

      Thermal conductivity, electrical conductivity, and permeability

  • 21. 
    Doubling the number of turns on a coil will:
    • A. 

      Double the inductance

    • B. 

      Halve the inductance

    • C. 

      Decrease the inductance by a factor of 4

    • D. 

      Increase the inductance by a factor of 4

  • 22. 
    Frequency ratio f/f can be defined as:
    • A. 

      The argument of the mathematical function describing the electromagnetic field within the test specimen

    • B. 

      Test frequency divided by limit frequency

    • C. 

      Neither

    • D. 

      Both

  • 23. 
    When testing tubing, using an encircling (OD) coil, What is the phase relationship of the output signals from identical ID and OD discontinuities?
    • A. 

      The signals are in phase

    • B. 

      The phase of the OD discontinuity leads the phase of the ID discontinuity

    • C. 

      The phase of the OD discontinuity lags the phase of the ID discontinuity

    • D. 

      Indeterminate

  • 24. 
    A term used to define an instrumentation technique which discriminates betweenvariables in the test part by the different phase angle changes which these conditionsproduce in the test signal is:
    • A. 

      Phase distortion

    • B. 

      Phase shifting

    • C. 

      Phase discrimination

    • D. 

      Phase analysis

  • 25. 
    If the characteristic frequency (fq) of a material is 125 hz, the test frequency required to give an f/fq ratio of 10 would be:
    • A. 

      1.25 Hz

    • B. 

      12.5 Hz

    • C. 

      1.25 kHz

    • D. 

      12.5 kHz