Snell's Law : A new law I am introducing today. Deals with the angles we looked at in the activity. Use your calculator to find sine for each angle.
where sin i is the sine of the angle of incidence, sin R is the sine of the angle of refraction, and n (index of refraction) is a constant.
Snell's Law in this format only works when going from air into another medium.
2. The incident ray and refracted ray are on opposite sides of the normal at the point of incidence.
3. The incident ray, refracted ray, and the normal all lie in the same plane.
1.
The speed of light in plastic is 2.00 x 10 8 m/s. What is the refractive index of the plastic?
N=c/v  3.00 x 10 8 m/s  n=1.5
2.00 x 10 8 m/s
2.
Given the speed of light in air is 3.00 x 10 8 m/s, find the speed of light in: a.
fused quartz n=1.46 b.
flint glass n=1.57 (from your refraction website activity) a) n=c/v  v=c/n  3.00 x 10 8 m/s  v= 2.05 x 10 8 m/s
1.46
3.
What is the index of refraction of a medium if the angle of incidence in air is 63º and the angle of refraction is 38º?
Here is where you use the new formula because you have angles sin i = n sin r n= sin
63º = 0.89 =1.43
sin 38º 0.62

4.
What is the angle of refraction in a medium if the angle of incidence in air is 48º and the index of refraction of the medium is 1.58?
1.58= sin
48º  sin r = sin
48º = 0.74 =sin 0.47 = 28 º
sin r 1.58 1.58 to get the answer in degrees you need to use the sin -1 button
5.
Light travels from air into water. What is the angle of incidence if the angle of refraction is 30º? If the speed of light in a liquid is
2.25 x 10 8 m/s, what is: a) the refractive index of the liquid? b) the identity of the liquid?
A) n= c/v= 3.00 x 10 8 m/s =1.33
2.25 x 10 8 m/s b) check with the list of refractive indexes under liquids and water should have an index of 1.33. It also said in the question.
6.
What is the speed of light in plexiglass?
B)
N=c/v  v=c/n  3.00 x 10 8 m/s =2.00 x 10 8 m/s
1.5