折射率 光密光疏一問

錯誤在於：「1.+2.→5.空氣=光密介質 玻璃=光疏介質」

原因：
空氣折射率為1，玻璃折射率為1.5。
光疏介質的折射率較小，光密介質的折射率較大。
因此，空氣是光疏介質，玻璃是光密介質。

Refractive index of a medium = c/v
where c is the speed of light in vacuum, and v is the speed of light in the medium.
For air, n(air) = c/v(air)
For glass, n(glass) = c/v(glass)
since glass is optically denser than air (because glass has a higher permeability and permitivity than air), light travels slowerly in glass than in air.
Therefore, n(glass) > n(air)
[NB: since v(air) is about the same as c, it is normally taken v(air)= c in calculations, and hence n(air) is more or less equal to 1]