Refraction of Light

Refraction

the bending of light as it passes from one medium to another of different optical density

Incident ray

the light ray going towards the surface

refracted ray

the light ray that enters a medium and undergoes a change of direction

point of incidence

the point at which the incident ray strikes the surface

normal

the perpendicular line to the surface at the point of incidence

angle of incidence

the angle between the incident ray and the normal

angle of refraction

the angle between the refracted ray and the normal

refractive index

the ratio of the speed of light in vacuum to the speed of light in the medium

laws of refraction

1. the incident ray, refracted ray and the normal at the point of incidence all lie in the same plane

2. Snell’s Law: for 2 given media, the ratio of the sine of the angle of incidence to the sine of the angle of refraction is a constant (sin i / sin r = constant)

total internal reflection

the complete reflection of light in a optically denser medium at the boundary with an optically less dense medium

critical angle

the angle of incidence in an optically denser medium for which the angle of refraction in the optically less dense medium is 90 degrees

conditions for total internal reflection

• light travels from an optically denser to an optically less dense medium

• angle of incidence in the optically denser medium is larger than the critical angle