Refraction 2

Refractive index in terms of relative speed:

N= c1/c2 = c air or vacuum/ medium

Where c is speed of light and n is refractive index.

(speed of light in air in log tables)

Critical angle (C) :

When light travels from a dense medium to a less dense medium and the angle of incidence whose corresponding angle of refraction is 90 degrees is called the critical angle.

(Density = mass/ volume)

Total internal reflection:

When light going from an else medium to a less dense medium strikes the second medium with an angle of incidence greater than the critical angle the light is reflected within the denser medium.

Refractive Index:

If the second medium is air:

xNa = Sin C

aNx = 1/Sin C

*We use this formula because C and Total Internal Reflection is always when going into a less dense medium and we are looking for refractive index of air to medium (not medium to air)

*Note: If you see the phrase “refractive index of glass is 1.5”, it means that when light travels from air to glass the refractive index is 1.5