Materials and Components - Section 1 (2)
Materials and Components - Section 1
| 9. | Assertion (A): In a perfect capacitor, the current density is given by ω ∈0E0∈'rcos(ωt + 90°), where ∈r' is real part of dielectric constant. Reason (R): In a perfect capacitor, dielectric losses are zero. |
|||||||
Answer: Option A Explanation: If dielectric losses are zero, the current in capacitor leads the applied voltage by 90°. Also imaginary part of is ∈r is zero. |
| 10. | If n denotes principal quantum number, the angular quantum number l = 0, 1... (n - 1). |
|||
Answer: Option A Explanation: Angular quantum number determines the angular momentum of electron. |
| 11. | Assertion (A): For Diamond, μr = 1 Reason (R): Diamond is a diamagnetic material. |
|||||||
Answer: Option A Explanation: For diamagnetic materials μr = 1. |
| 12. | Assertion (A): Power loss in a conductor of resistance P = I2R. Reason (R): When a conductor is carrying current with current density J as a result of applied field E, then heat developed/m3/ second = JE. |
|||||||
Answer: Option A Explanation: Heat developed depends an power loss. |
| 13. | Ferroelectric materials are those which |
|||||||
Answer: Option B Explanation: Ferroelectric materials have permanent polarization. |
| 14. | At room temperature, the current in intrinsic semiconductor is due to |
|||||||
Answer: Option D Explanation: Both electrons and holes contribute to flow of current in semiconductors. |
| 15. | Assertion (A): At a temperature of 1000 K, thermionic emission current is about 0.1 A/cm2 of surface. Reason (R): Thermionic emission current is given by Ith = SA0 T2 e-Ew/kT. |
|||||||
Answer: Option A Explanation: If different values are substituted in the equation for Ith the value of emission current comes out to be about 0.1 A/cm2. |
| 16. | If ∈r' and ∈r" are the real and imaginary parts of complex dielectric constant ∈r, and δ is the loss angle. Then |
|||||||
Answer: Option B Explanation: If ∈r" = 0, δ = 0. |
