Discussion
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- Question
The magnetic quantum number determines the component of angular momentum along a prescribed direction.
Options- A. True
- B. False
- Correct Answer
- True
- 1. Wood is a diamagnetic material.
Options- A. True
- B. False Discuss
- 2. The phenomenon of dielectric hysteresis occurs with
Options- A. dc
- B. ac
- C. both ac and dc
- D. none of the above Discuss
- 3. The elements which become superconducting at extremely low temperatures are
Options- A. good conductors at room temperature
- B. ferromagnetic at room temperature
- C. relatively poor conductors at room temperature
- D. insulators at room temperature Discuss
- 4. Which of the following are true for relative dielectric constant?
- It is dimensionless.
- It is equal to 1 for vacuum.
- It is equal to 1 for all substances.
Options- A. 1 and 2 only
- B. 2 and 3 only
- C. 1 and 3 only
- D. 1, 2 and 3 Discuss
- 5. The residual resistivity of a binary alloy at 0 K is
Options- A. sum of residual resistivities of component metals
- B. difference of residual resistivities of component metals
- C. product of residual resistivities of component metals
- D. dependent on the concentration of minor component in the alloy Discuss
- 6. In an intrinsic semiconductor, at a given temperature T
Options- A. the number of electrons-hole pairs generated per second due to thermal motion are equal to the number of electron-hole pairs lost per second due to recombination
- B. the number of electron-hole pairs generated per second due to thermal motion is always less than the number of electron-hole pairs lost per second due to recombination
- C. the number of electron hole pairs generated per second due to thermal motion is always more than the number of electron-hole pairs lost per second due to recombination
- D. any of the above Discuss
- 7. Curie Weiss law is
.
Options- A. True
- B. False Discuss
- 8. Electrical contact materials used in switches, brushes, relay must possess
Options- A. high thermal conductivity and high melting point
- B. low thermal conductivity and low melting point
- C. high thermal conductivity and low melting point
- D. low thermal conductivity and high melting point Discuss
- 9. The unit for mmf is
Options- A. A
- B. Wb
- C. T
- D. V Discuss
- 10. If a small amount of Cu is added to Ni conductor, then
Options- A. resistivity of Ni will decrease at all temperatures because Cu is a better conductor than Ni
- B. residual resistivity of Ni at low temperature will increase as Cu atoms act as defect centres
- C. resistivity of Ni will increase at all temperatures as Cu destroys the periodicity of Ni and acts as defects
- D. resistivity of Ni remains the same Discuss
Materials and Components problems
Search Results
Correct Answer: False
Correct Answer: ac
Explanation:
Hysteresis phenomenon occurs when direction of electric field is changed. This can happen only with ac.
Correct Answer: relatively poor conductors at room temperature
Correct Answer: 1 and 2 only
Explanation:
?r has no units and equal to 1 for vacuum. For other substances it has different value.
Correct Answer: dependent on the concentration of minor component in the alloy
Correct Answer: the number of electrons-hole pairs generated per second due to thermal motion are equal to the number of electron-hole pairs lost per second due to recombination
Correct Answer: True
Correct Answer: high thermal conductivity and high melting point
Explanation:
Heat generated at contact should be dissipated quickly and contact should not melt.
Correct Answer: A
Correct Answer: resistivity of Ni will increase at all temperatures as Cu destroys the periodicity of Ni and acts as defects
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