2 May 2013 ... P10 Snell's Law & the Index of Refraction. 1 ... The speed of light travels at a
constant speed of 299 792 458 m/s in a ... EXAMPLE PROBLEM.
P10 Snell's Law & the Index of Refraction
May 02, 2013
THE SPEED OF LIGHT AND REFRACTION detailed powerpoint on the history of the speed of light
The speed of light travels at a constant speed of 299 792 458 m/s in a vacuum. Big numbers are usually written in scientific notation. This would become
When rounded to 2 decimal places, this value would become
The symbol for this constant is _____.
Although the speed of light is a constant, this value changes when light changes mediums. The term "index of refraction" refers to the ratio of the speed of light in a vacuum compared the speed of light in a given medium. Written mathematically,
c n = v
where • n is the "index of refraction" • c always equals 3.00 x 108 m/s • v is the speed of light in the medium in question There are no units for n because _____________________________________________ Use the following table to find the speed of light in water, glass and diamond.
lucite
1.495 In which medium does light travel the slowest?
1
P10 Snell's Law & the Index of Refraction
May 02, 2013
SNELL's LAW WITH THE INDEX OF REFRACTION After the speed of light was determined for different materials, scientists discovered that the ratio of their indexes of refraction coincided with Snell's law.
sinθi = constant value sinθr
=
nr ni
where n r refers to the medium with the refracted ray, and n i refers to the medium with the incident ray.
sinθi nr = Historically the equation is written as but it is easier to work with if the sinθr ni equation is written as
ni sinθi = nr sinθr
EXAMPLE PROBLEM A flashlight is aimed towards the water at an angle of 30o. What angle does it travel at in the water?
Homework Questions 1. Determine the speed of light in polystyrene plastic. 2. The speed of light in medium x is 1.53 x 108 m/s. What is the medium? 3. A ray of light in air is approaching the boundary with water at an angle of 52 degrees. Determine the angle of refraction of the light ray. 4. A ray of light in air is approaching the boundary with a layer of crown glass at an angle of 42.0 degrees. Determine the angle of refraction of the light ray upon entering the crown glass and upon leaving the crown glass. Refer to the table of indices of refraction if necessary. 5. Light travels from air into an optical fiber with an index of refraction of 1.44. (a) In which direction does the light bend?
o, what is the angle of (b) If the angle of incidence on the end of the fiber is 22 refraction inside the fiber?
(c) Sketch the path of light as it changes media. o above the horizon but 6. A scuba diver is unaware of the time. The sun is only 10 the scuba diver thinks the sun is much higher in the sky. At what angle does she think the sun is at? Sketch out the problem to help you interpret the question.
