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what is the refractive index of a material?
the speed of light in a vacuum divided by the speed of light in the material
the greater the refractive index…..
the more the light entering the material is refracted towards the normal
Snell’s law of refraction
n1 sin(angle of incidence)= n2 sin(angle of refraction)
what is the critical angle?
the critical angle is the angle of incidence required for the angle of refraction to be 90, so light refracts along the boundary between the two media
what is total internal reflection?
when the light strikes the boundary at a large angle, it is totally internally reflected
all the light is reflected back into the original medium
no light is refracted out of the original medium
what is the first condition for TIR?
the light must be travelling through a medium with a higher refractive index as it strikes the boundary with a medium with a lower refractive index (eg when light in glass meets air)
what is the second condition for TIR?
the angle at which the light strikes the boundary must be above the critical angle
the greater the refractive index……
the lower the critical angle
Note
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