Discussion
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- Question
In a specimen of ferromagnetic material, as the flux density is increased from zero to 2.5 T, µr will
Options- A. increase
- B. decrease
- C. first decrease then increase
- D. first increase then decrease
- Correct Answer
- first increase then decrease
- 1. A 200 turn coil has a self inductance of 10 mH. If the number of turns is doubled, all other quantities remaining the same, the self inductance will be
Options- A. 2.5 mH
- B. 5 mH
- C. 20 mH
- D. 40 mH Discuss
- 2. The field pattern of a solenoid is similar to that of bar magnet.
Options- A. True
- B. False Discuss
- 3. A material which is lightly repelled by a magnetic field is known as
Options- A. diamagnetic material
- B. non-magnetic material
- C. ferromagnetic material
- D. paramagnetic material Discuss
- 4. The relationship of hysteresis loss to maximum flux density was first determined by
Options- A. C. Steinmetz
- B. G.R. Kirchoff
- C. Mr. Laplace
- D. Mr. Ampere Discuss
- 5. The heat developed per m3 per second (W) in a conductor having a conductivity ? and a field E is
Options- A. W = ?E2
- B. W = ?E
- C. W =
- D. W = (?E)0.5 Discuss
- 6. The number of valence electrons in acceptor impurity are
Options- A. 5
- B. 4
- C. 3
- D. 1 Discuss
- 7. Ferrites have
Options- A. a low copper loss
- B. low eddy current loss
- C. low resistivity
- D. higher specific gravity compared to iron Discuss
- 8. A permeable substance is one
Options- A. which is strong magnet
- B. which is a weak magnet
- C. which is a good conductor
- D. through which magnetic lines of force can pass easily Discuss
- 9. Which of the following is the poorest conductor of electricity?
Options- A. Aluminium
- B. Nichrome
- C. Copper
- D. All of the above Discuss
- 10. In a pure sample of silicon
Options- A. the number of holes and free electrons is always equal
- B. the number of free electrons is more than the number of holes
- C. the number of free electrons and holes is equal at low temperature
- D. the number of free electrons is less than number of holes Discuss
Materials and Components problems
Search Results
Correct Answer: 40 mH
Explanation:
Inductance is proportional to square of number of turns.
Correct Answer: True
Correct Answer: diamagnetic material
Correct Answer: C. Steinmetz
Correct Answer: W = ?E2
Correct Answer: 3
Correct Answer: low eddy current loss
Explanation:
Resistivity of ferrites is very high as compared to that of iron. Hence eddy curretns are much less.
Correct Answer: through which magnetic lines of force can pass easily
Correct Answer: Nichrome
Correct Answer: the number of holes and free electrons is always equal
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