Do Now: Light passes from air into some corn oil used for baking. What is the velocity of light in corn oil? How does this compare to light in glycerol? What class and type of wave is light? What does it mean for light to be polarized?

Aim: How Can We Determine How Much Light Is Bent?

How does the speed of light in two mediums relate to each other? Lets look at light traveling in two different mediums, shall we? FREQUENCY IS CONSTANT What is missing? Why?

Sample Problems If a light ray from air travels into water and the water has an index of refraction of 1.33, then what is the speed of light in water? What is the wavelength in water if it’s 600 nm in air?

Describe what’s happening! The incident ray of light slows down in the medium The wavelength is shorter in the different medium The frequency remains constant!

Helps us determine how much light bends! Snell’s Law (Law of Refraction) Helps us determine how much light bends!

How Much Does Light Bend? n1=Air If the angle of incidence with respect to the normal line was 60 degrees, then how much would the light bend? n2=Water

Law of Refraction: Snell’s Law As waves enter a new medium they BEND Moving into a SLOWER medium bends a wave TOWARD the normal and wavelengths SHORTEN Moving into a FASTER medium bends a wave AWAY from the normal and wavelengths LENGTHEN In either case, FREQUENCY IS CONSTANT

Normal Example #1 50° 50° Air n1 = 1.00 Flint Glass n2 = 1.66 θ2 A ray of light with a frequency of 5x1014 Hz moves from air into a piece of flint glass. The ray strikes the glass at an angle of 50º with the normal. What happens to this ray of light and calculate the refracted angle in the flint glass. Normal Partial Reflection 50° 50° Air n1 = 1.00 Flint Glass n2 = 1.66 θ2

White Board Activity Using the white boards, answer the following parts of the question given.

Example #2 A ray of violet light (7.69x1014Hz) moving through diamond enters water at an angle of 30º relative to a normal drawn from its point of entry. a) Determine the speed of light when it is in the diamond b) Calculate the wavelength of the light in the diamond d) Calculate the angle the light will bend at when it exits into the water c) What will be the wavelength of the light when it exits into the water?

Mid Review Card Describe the Law of Reflection What happens when light hits a bumpy surface? How does a Refracted ray of light behave when it enters a… Denser Medium? Lighter Medium? Even when light enters a different medium, what stays constant? How can you calculate the refracted angle of a light ray? What are some other useful equations to keep in mind?

Corn Oil: n = 1.47 Glycerol: n = 1.47 Use Snell’s Law to identify the angle of refraction in ALL mediums and the angle of reflection at the mirror base.

What is the difference? n1Sinθc = n2Sin(90o) Critical Angle: Smallest angle of Incidence for which light is totally reflected Draw 3 different refraction ray diagrams with increasing angle for diamond into air. Show how slowly the ray will bend towards the medium boundary until it is 90 degrees off normal line at critical angle. The Critical Angle occurs when the refracted angle is 90 degrees. n1Sinθc = n2Sin(90o)

Demo: Critical angle of a waterfall

Practice What is the critical angle for a light ray traveling from diamond into corn oil? What occurs when light hits the diamond at an angle greater than the critical angle?

Exit Card Use your knowledge of friction to answer the questions on your exit card. Be sure to hand in your exit card when it is complete.

What are the three main formulas regarding refraction? Explain what each formulas describes. Describe the critical angle!