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Magnetism and Electromagnetism problems


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

  • Options
  • A. armature
  • B. field winding
  • C. commutator
  • D. brush
  • Discuss
  • 2. 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
  • 3. 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
  • 4. 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
  • 5. Which electromagnetic device uses brushes and a commutator?

  • Options
  • A. A speaker
  • B. A dc generator
  • C. A relay
  • D. A solenoid
  • Discuss
  • 6. 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
  • 7. What are the effects of moving a closed wire loop through a magnetic field?

  • Options
  • A. A voltage is induced in the wire.
  • B. A current is induced in the wire.
  • C. The polarity across the wire depends on the direction of motion.
  • D. All of the above
  • Discuss
  • 8. Which electromagnetic device has a movable iron core called a plunger?

  • Options
  • A. A speaker
  • B. A dc generator
  • C. A relay
  • D. A solenoid
  • Discuss
  • 9. Which electromagnetic device has a flexible cone?

  • Options
  • A. A speaker
  • B. A dc generator
  • C. A relay
  • D. A solenoid
  • Discuss
  • 10. What is the magnetomotive force in a 150-turn coil of wire with 2 A flowing through it?

  • Options
  • A. 13.33 mAt
  • B. 300 At
  • C. 75 At
  • D. 152 At
  • Discuss

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