Materials and Components problems
- 1. Curie Weiss law is
.
Options- A. True
- B. False Discuss
Correct Answer: True
- 2. 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
Correct Answer: high thermal conductivity and high melting point
Explanation:
Heat generated at contact should be dissipated quickly and contact should not melt.
- 3. The unit for mmf is
Options- A. A
- B. Wb
- C. T
- D. V Discuss
Correct Answer: A
- 4. 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
Correct Answer: resistivity of Ni will increase at all temperatures as Cu destroys the periodicity of Ni and acts as defects
- 5. 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
Correct Answer: 2 N, - y direction
- 6. 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
Correct Answer: the field inside the cavity must be made stronger than field outside the cavity
- 7. Assertion (A): Hall effect is used to determine whether the semi- conductor is p or n type.
Reason (R): Under the influence of field, holes and electrons move in opposite direction.
Options- A. Both A and R are true and R is correct explanation of A
- B. Both A and R are true but R is not correct explanation of A
- C. A is true but R is false
- D. A is false but R is true Discuss
Correct Answer: Both A and R are true and R is correct explanation of A
- 8. In terms of Planck's constant h, the orbital angular momentum of an electron is
Options- A. h
- B.
- C. 2ph
- D.
Discuss
Correct Answer:
- 9. The induced magnetic dipole moment is independent of the permanent magnetic dipole moment.
Options- A. True
- B. False Discuss
Correct Answer: True
- 10. When a material is in superconducting state and a magnetic field is applied
Options- A. the superconducting property is not affected
- B. the superconducting property may be affected and resistivity may increase from zero to a low value
- C. the superconducting property may be destroyed
- D. the material may become an insulator Discuss
Correct Answer: the superconducting property may be destroyed
More in Electronics and Communication Engineering:
Programming
Copyright ©CuriousTab. All rights reserved.