380 likes | 1.01k Views
Refraction of Light. When light travels from one medium into another, it bends. The bending of light in this way is called Refraction . Why does light bend?. Assuming that a car travels slower on gravel than on concrete … picture this …. Gravel (thick medium). Gravel (thick medium).
E N D
When light travels from one medium into another, it bends. The bending of light in this way is called Refraction.
Why does light bend? • Assuming that a car travels slower on gravel than on concrete … picture this … Gravel (thick medium) Gravel (thick medium) Gravel (thick medium) Concrete Road (thin medium) Concrete Road (thin medium) Concrete Road (thin medium)
Air Water
Refraction of Light (< of incidence) (< of reflection) Normal Reflected Ray Incident Ray Өi Өr Refracted Ray ӨR (< of Refraction)
Some substances cause light to slow down more than others. Hence, these substance cause light to bend more than others.
The Index of Refraction for any material is a comparison of the speed of light in the material to the speed of light in a vacuum (c) Speed of light in a vacuum Index of Refraction Speed of light in the material
Examples • The speed of light in a vacuum is 3.0 x 108 m/s. When light travels through ice, it slows down to 2.29 x 108 m/s. Determine the index of refraction for ice. • If the index of refraction for diamond is 2.42, how fast does light travel as it passes through?
The Law of Refraction • In 1621, Willebrord Snellius derived a mathematical equation to predict how light will refract when it travels between two different mediums.
Snell’s Law Air n = 1.000293 θR θi Glass n = 1.52
Snell’s Law Air n = 1.000293 θR θi Glass n = 1.52
Snell’s Law Air n = 1.000293 θR θi Glass n = 1.52
Snell’s Law Air n = 1.000293 θR θi Glass n = 1.52
Example • Light enters water (n = 1.33) from air (n = 1.000293) at an angle of 25o. With what angle does it refract? • Light travels from glass (n = 1.52) into another substance at an angle of 45o. If it refracts at an angle of 26o, what is the substance?