PHY問題---為何紫光進入三綾鏡後折射較紅光大?

No. The above answer is completely irrelevant.

Rayleighs Law (瑞利定律) only applies to scattering (散射) of light by particles, but does not apply to refraction (折射) of light in a medium.

The degree of refraction depends on the speed of light in the medium. The lower the speed, the higher the refractive index (since refractive index is the ration of speed of light in vacuum to that in the medium) and hence the more the refraction is.

Violet light travels slower than red light in (glass) prism, thus subject to more refraction than red light does.

You may also refer to the following explanation, which is extrated from my previous answer to a similar question, on why the speed of light of different frequency (i.e. different colour) is different in glass.

[From classical electromagnetic theory developed by Clark Maxwell in the late 19 Century (the Maxwells equations), it has been shown that the speed of electromagnetic waves (EM waves) depends on the electric property (the permitivity) and magnetic property (the permeability) of a medium in which the EM wave passes through. The reason being that EM wave travels by changing electric and magnetic fields. These changing electric and magnetic fields will interact with the atomic dipoles of the medium, thus affecting the wave speed.

The higher the permitivity or permeability of a material, the lower is the light speed because of strong interaction of the atomic dipoles with the electric and magnetic fields of the EM wave. Because vacuum has the lowest permitivity and permeability, thus EM wave (and light, which is EM wave in nature) travels fastest in vacuum.

Both permitivity and permeability are frequency dependent. In the visible range, red light (which has the lowest frequency) has the lowest permitivity and permeability among other coloured lights in glass, thus having the highest speed. On the other hand, violet light travels slowest in the same medium because the permitivity and permeability for violet light are the highest.]

這是由於可見光中紫光的波長最短(400奈米)，跟據細微質點的折射遵循瑞利定律--折射光強度與波長的四次方成反比。

所以紫光折射較紅光大
如果你又問紫光的波長為何是最短，這個就要問上帝了:)