Magnetism and Electromagnetism problems
- 1. A coil of wire is placed in a changing magnetic field. If the number of turns in the coil is decreased, the voltage induced across the coil will
Options- A. increase
- B. decrease
- C. remain constant
- D. be excessive Discuss
Correct Answer: decrease
- 2. A basic one-loop dc generator is rotated at 90 rev/s. How many times each second does the dc output voltage peak (reach maximum)?
Options- A. 90
- B. 180
- C. 270
- D. 360 Discuss
Correct Answer: 180
- 3. What is the flux density when the flux is 5.5 µWb and the cross-sectional area is 6 × 10?3 m2?
Options- A. 91.7 µT
- B. 917 µT
- C. 91 T
- D. 9.7 T Discuss
Correct Answer: 917 µT
- 4. If the steel disk in a crankshaft position sensor has stopped with the tab in the magnet's air gap, the induced voltage
Options- A. increases
- B. decreases
- C. is zero
- D. will remain constant Discuss
Correct Answer: is zero
- 5. A relay is an electromagnetically controlled mechanical device in which electrical contacts are opened or closed by a magnetizing current.
Options- A. True
- B. False Discuss
Correct Answer: True
- 6. If a conductor is moved back and forth at a constant rate in a constant magnetic field, the voltage in the conductor will reverse polarity.
Options- A. True
- B. False Discuss
Correct Answer: True
- 7. Ampere-turn is the unit of magnetomotive force (mmf).
Options- A. True
- B. False Discuss
Correct Answer: True
- 8. The tesla is the unit of magnetic flux.
Options- A. True
- B. False Discuss
Correct Answer: False
- 9. Materials with a low retentivity do not retain a magnetic field very well.
Options- A. True
- B. False Discuss
Correct Answer: True
- 10. Hysteresis is the number of lines of force per unit area in a magnetic field.
Options- A. True
- B. False Discuss
Correct Answer: False
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