4. (a) Many gases can be characterized by a single resonant frequency wo; also, the density is often low enough so that

[answerhappygod]

4 A Many Gases Can Be Characterized By A Single Resonant Frequency Wo Also The Density Is Often Low Enough So That 1 (32.16 KiB) Viewed 46 times

4. (a) Many gases can be characterized by a single resonant frequency wo; also, the density is often low enough so that the plasma frequency is small compared to wp. For these materials, starting from Eq. (9.161), show that the index of refraction is approximately 1+ 2(w²w²) [Assume f = 1, i.e., that every electron in the molecule participates in the resonance.] (b) In the visible, the index of refraction of air at STP is 1.00029. [Hint: You will want to show that the density of nitrogen molecules at STP is 3.8 x 1026 m.] Use this fact to estimate o for N₂. [Answer: 4.5 x 10¹6 rad/s (in the ultraviolet).]