Discussion
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- Question
Curie Weiss law is
.
Options- A. True
- B. False
- Correct Answer
- True
- 1. 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
- 2. The magnetic quantum number determines the component of angular momentum along a prescribed direction.
Options- A. True
- B. False Discuss
- 3. Wood is a diamagnetic material.
Options- A. True
- B. False Discuss
- 4. The phenomenon of dielectric hysteresis occurs with
Options- A. dc
- B. ac
- C. both ac and dc
- D. none of the above Discuss
- 5. 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
- 6. 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
- 7. The unit for mmf is
Options- A. A
- B. Wb
- C. T
- D. V Discuss
- 8. 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
- 9. A conductor carries 10 A current in + x direction and is lying in a field having a flux density 0.2 T directed along + z direction. The magnitude of force per metre length and direction are
Options- A. 2 N, + y direction
- B. 2 N, - y direction
- C. 0.02 N, + y direction
- D. 0.02 N, - y direction Discuss
- 10. The core of a solenoid is made of material of relative permeability ?r. A small cavity area dA and length dl is cut in the core. If it is desired that flux density in the cavity should be equal to B0
Options- A. the fields inside and outside the cavity must be equal
- B. the field inside the cavity must be made stronger than field outside the cavity
- C. the field inside the cavity must be made weaker than the field outside the cavity
- D. none of the above Discuss
Materials and Components problems
Search Results
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: 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: 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
Correct Answer: 2 N, - y direction
Correct Answer: the field inside the cavity must be made stronger than field outside the cavity
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