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Current Concept and Measurement

Current Concept and Measurement Definition of Current Current is formed by directional movement of charges, representing the amount of charge passing through a…

About 5 min read beginner
CurrentMeasurementSafetyBasics

Current Concept and Measurement

Definition of Current

Current is formed by directional movement of charges, representing the amount of charge passing through a conductor's cross-section per unit time.

Formula

I = Q / t
  • I: Current (A)
  • Q: Charge quantity (C)
  • t: Time (s)

    • Current Units

    UnitSymbolConversion
    AmpereABase unit
    MilliamperemA1A = 1000mA
    MicroampereμA1mA = 1000μA

    Current Direction

  • Conventional direction: Direction of positive charge movement
  • Actual current: Electron movement direction is opposite to conventional direction
  • In circuits: Flows out from positive terminal, returns to negative terminal

    • Current Types

    DC Current

  • Direction is constant
  • Magnitude may be constant or pulsating

    • AC Current

  • Direction changes periodically
  • Represented by RMS value

    • Measurement Methods

    Multimeter Measurement

  • Disconnect the circuit
  • Connect multimeter in series
  • Select appropriate range
  • Read the value

    • Clamp Meter Measurement

  • No need to disconnect circuit
  • Clamp around the wire
  • Read the value
  • Suitable for large current measurement

    • Safe Current

    Current LevelHuman Sensation
    <1mANo sensation
    1-8mATingling sensation
    8-15mADifficult to let go
    >50mADangerous!
    After reading

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