Discussion
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- Question
What is the magnetomotive force (mmf) of a wire with 8 turns carrying three amperes of current?
Options- A. 2,400 At
- B. 240 At
- C. 24 At
- D. 2.4 At
- Correct Answer
- 24 At
- 1. When the north poles of two bar magnets are brought close together, there will be
Options- A. no force
- B. a downward force
- C. a force of attraction
- D. a force of repulsion Discuss
- 2. What is the magnetomotive force in a 75-turn coil of wire when there are 4 A of current through it?
Options- A. 18.75 At
- B. 30 At
- C. 300 At
- D. 187 At Discuss
- 3. The ability of a material to remain magnetized after removal of the magnetizing force is known as
Options- A. permeability
- B. reluctance
- C. hysteresis
- D. retentivity Discuss
- 4. When the speed at which a conductor is moved through a magnetic field is increased, the induced voltage
Options- A. increases
- B. decreases
- C. remains constant
- D. reaches zero Discuss
- 5. The direction of a magnetic field within a magnet is
Options- A. from south to north
- B. from north to south
- C. back to front
- D. front to back Discuss
- 6. What is the flux density in a magnetic field in which the flux in 0.1 m2 is 600 µWb?
Options- A. 6,000 µT
- B. 600 µT
- C. 600 T
- D. 6 T Discuss
- 7. The induced voltage across a coil with 250 turns that is located in a magnetic field that is changing at a rate of 8 Wb/s is
Options- A. 1,000 V
- B. 2,000 V
- C. 31.25 V
- D. 3,125 V Discuss
- 8. The unit for reluctance is
Options- A. tesla
- B. At/Wb
- C. At/m
- D. Wb Discuss
- 9. If a loop in a basic dc generator suddenly begins rotating at a faster speed, the induced voltage
Options- A. remains unchanged
- B. reverses polarity
- C. increases
- D. decreases Discuss
- 10. When the current through the coil of an electromagnet reverses, the
Options- A. direction of the magnetic field reverses
- B. direction of the magnetic field remains unchanged
- C. magnetic field expands
- D. magnetic field collapses Discuss
Magnetism and Electromagnetism problems
Search Results
Correct Answer: a force of repulsion
Correct Answer: 300 At
Correct Answer: retentivity
Correct Answer: increases
Correct Answer: from south to north
Correct Answer: 6,000 µT
Correct Answer: 2,000 V
Correct Answer: At/Wb
Correct Answer: increases
Correct Answer: direction of the magnetic field reverses
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