<aside> 🔆 Snell’s law describes the relationship between the incident and refracted angles of a light ray and the indices of refraction of two media: $n_1 \sin \theta_1 = n_2 \sin \theta_2$

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• The index of refraction, $n$, of a medium is the ratio of the speed of light in a vacuum, $c$, to the speed of light in the medium $n = \frac{c}{v}$

  

  the speed of light and indices of refraction in various media

• The index of refraction, $n$, of a medium is equal to the ratio of the wavelength of light in a vacuum, $\lambda_1$, to the wavelength of light in the medium, $n = \frac{\lambda_1}{\lambda_2}$

  • For two different media, $\frac{n_1}{n_2} = \frac{\lambda_1}{\lambda_2}$, the frequency of light is unchanged
  • To find the wavelength in a new medium: $\lambda_{new} = \frac{\lambda_{original}}{n_{new}}$

• Dispersion is the separation of a wave into its component parts according to a given characteristic, such as wavelength

• When light passes from one medium to another, partial reflection and partial refraction can occur, and the wavelength changes based upon the index of refraction for the second medium

Total internal reflection occurs when light is completely reflected at a boundary between two media

1. The incident light must originate in the more optically dense medium

2. The angle of incidence must be greater than the critical angle

   

The critical angle can be calculated using $\theta_c = sin^{-1} (\frac{n_2}{n_1})$