Discussion
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- Question
When a dielectric material is subjected to alternating field, the absorption of energy by the material from the field is given by the imaginary part of polarizability.
Options- A. True
- B. False
- Correct Answer
- True
- 1. The merger of hole and free electron is called
Options- A. covalent bonding
- B. recombination
- C. thermal energy
- D. free electrons Discuss
- 2. Assertion (A): Resistivity of a perfect single crystal of a metal goes to zero as T approaches zero.
Reason (R): Scattering of electrons is due to deviations from perfect periodicity of lattice.
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
- 3. If t is relaxation time and tc is average time between collisions, then in an isotropic metal
Options- A. t = tc
- B. t < tc
- C. tc < t
- D. T = 0.01 te Discuss
- 4. The materials which become polarized on the application of mechanical stress are called piezoelectric.
Options- A. True
- B. False Discuss
- 5. A wire is carrying current I. The field intensity H at a distance r from the wire
Options- A. is directed towards wire
- B. is directed away from wire
- C. is tangential every where to a circle of radius r
- D. none of the above Discuss
- 6. If the number of atoms per unit volume of a monoatomic gas changes, the dielectric constant still remains constant.
Options- A. True
- B. False Discuss
- 7. 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
- 8. 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
- 9. 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
- 10. The phenomenon of dielectric hysteresis occurs with
Options- A. dc
- B. ac
- C. both ac and dc
- D. none of the above Discuss
Materials and Components problems
Search Results
Correct Answer: recombination
Correct Answer: Both A and R are true but R is not correct explanation of A
Correct Answer: t = tc
Correct Answer: True
Correct Answer: is tangential every where to a circle of radius r
Correct Answer: True
Explanation:
The dielectric constant changes as it is proportional to the number of atoms per unit volume.
Correct Answer: dependent on the concentration of minor component in the alloy
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: relatively poor conductors at room temperature
Correct Answer: ac
Explanation:
Hysteresis phenomenon occurs when direction of electric field is changed. This can happen only with ac.
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