Final answer:
The critical angle is smaller for blue light compared to green light because blue light, having a shorter wavelength, refracts more and therefore has a higher index of refraction and a smaller critical angle in comparison to green light.
Step-by-step explanation:
The critical angle for light is the angle of incidence above which all light is reflected back into the medium rather than refracted through the boundary. Regarding whether the critical angle is greater for green light or blue light, it's essential to understand that the critical angle depends on the indices of refraction for the two materials and the wavelength of the light. Generally, shorter wavelengths, like blue light, refract more than longer wavelengths such as green light, implying that blue light would have a smaller critical angle compared to green light because it bends more upon entering a less dense medium.
In a material like diamond surrounded by air, red light (660 nm) and violet light (410 nm) have different critical angles due to the material's high refractive index. The index of refraction generally decreases with increasing wavelength, which means blue light (with a shorter wavelength) will have a higher index of refraction than green light and thus a smaller critical angle. Therefore, green light would have a larger critical angle relative to blue light.