Materials and Components – Section 5
12. | Assertion (A): Rochelle salt and Barium titanate are both ferroelectric.
Reason (R): Ferroelectric materials exhibit hysteresis effect. |
|||||||
Answer: Option B Explanation: Both the materials exhibit ferroelectric properties. Hysteresis effect is one of the features of ferroelectric materials. |
13. | The units for electric dipole moment are | |||||||
Answer: Option B Explanation: It is product of charge and distance. |
14. | The temperature coefficient of resistivity of semiconductors is | |||||||
Answer: Option B Explanation: Resistance of semiconductors decreases with increase in temperature. |
15. | Which of the following is used in automatic control of street lights? | |||||||
Answer: Option B |
16. | A leaky dielectric has ∈r = ∈r‘ – j∈r“. If a field E is applied, the current component in phase with E is proportional to ∈r“. | |||
Answer: Option A |
17. | Assertion (A): In ionic dielectrics, P = Pe + Pi.
Reason (R): In ionic crystals, permanent electric dipole moment is zero. |
|||||||
Answer: Option A Explanation: In ionic dielectrics μp = ∑i ei ri and Po = 0. Therefore P = Pe + Pi. |
18. | The current flow in a semiconductor is due to | |||||||
Answer: Option C |
19. | Assertion (A): Relative permittivity is determined by the atomic structure of the material.
Reason (R): Absolute permittivity is determined by the atomic structure of the material. |
|||||||
Answer: Option C |
20. | Eddy current loss is | |||||||
Answer: Option C |