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Home Electronics Magnetism and Electromagnetism Comments

  • Question
  • The component that produces power in an electromagnetic generator is called the


  • Options
  • A. armature
  • B. field winding
  • C. commutator
  • D. brush

  • Correct Answer
  • armature 


  • Magnetism and Electromagnetism problems


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    • 1. The unit for frequency is the

    • Options
    • A. hertz
    • B. ampere
    • C. watt
    • D. second
    • Discuss
    • 2. Add 21 mA and 8000 µA and express the result in milliamperes.

    • Options
    • A. 21.8 mA
    • B. 218 mA
    • C. 29 mA
    • D. 290 mA
    • Discuss
    • 3. Derived units are obtained from various combinations of

    • Options
    • A. electrical quantities
    • B. fundamental units
    • C. metric prefixes
    • D. international standards
    • Discuss
    • 4. The difference between scientific and engineering notation is

    • Options
    • A. powers of ten representation
    • B. single vs. multiple digits before decimal point
    • C. groupings of multiples of three digits
    • D. All of the above
    • Discuss
    • 5. 7200 mV is the same as

    • Options
    • A. 7.2 µV
    • B. 7.2 V
    • C. 7,200,000 V
    • D. 0.0072 µV
    • Discuss
    • 6. A Hall effect sensor

    • Options
    • A. exists only in theory
    • B. is a noncontacting magnetic sensor
    • C. can operate only a few times before failure
    • D. produces very large voltages
    • Discuss
    • 7. What is the reluctance of a material that has a length of 0.045 m, a cross-sectional area of 0.015 m2, and a permeability of 2500 µWb/At·m?

    • Options
    • A. 833.33 µAt/Wb
    • B. 0.27 At/Wb
    • C. 1200 At/Wb
    • D. More information is needed in order to find the reluctance.
    • Discuss
    • 8. What is the flux density of a magnetic field whose flux is 3000 µWb and cross-sectional area is 0.25 m2?

    • Options
    • A. 12,000 µT
    • B. 83,330 T
    • C. 0 T
    • D. More information is needed in order to find flux density.
    • Discuss
    • 9. Which electromagnetic device uses brushes and a commutator?

    • Options
    • A. A speaker
    • B. A dc generator
    • C. A relay
    • D. A solenoid
    • Discuss
    • 10. The Hall effect

    • Options
    • A. is a phenomenon with no practical applications
    • B. is used in various sensor applications
    • C. can develop potentials of thousands of volts
    • D. is the basis for solar cell operation
    • Discuss


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