Phy2005 Applied Physics II Spring 2017 Announcements:

Refraction: Snell’s Law Last time Refraction: Snell’s Law All three beams (incident, reflected, and refracted) are in one plane. q1 q2 Light always travels slower in a medium than in a vacuum, v=c/n v: speed of light in a medium n = c/v :index of refraction n > 1 v1 = c/n1, v2 = c/n2 n1sinq1 = n2sinq2

Dispersion: index of refraction decreases with wavelength! Air Water

In glass n (red) ≈ 1.51 n (purple) ≈ 1.53

q l(nm) 1  sin qred = nred sin 30o = nred/2 What is the angle between the red (4.6x1014 Hz) and blue (6.3x1014 Hz) rays emerging from a 30o prism as shown? 1.45 1.48 1.47 1.46 300 500 700 n, quartz l(nm) white 30o q nred=1.453 nblue=1.460 lred =c/f = (3.0 x 108m/s)/(4.6x1014 Hz) = 6.5 x 10-7m = 650 nm lblue =c/f = (3.0 x 108m/s)/(6.3x1014 Hz) = 4.8 x 10-7m = 480 nm 1  sin qred = nred sin 30o = nred/2  qred = Arcsin (nred/2) = 0.813 rad qblue = Arcsin (nblue/2) = 0.818 rad qblue- qred = q = 0.005 rad = 0.28 degrees

http://science.howstuffworks.com/

“rainbow angle” = 42 degrees

Reminder- last time some of you had trouble here: There are three layers of different media as shown in the figure. A beam of light bends as shown in the figure when it passes through the media. What can we say about the relative index of refraction of these materials? The media I-II-III have indices of refraction that get smaller 2) One of the media is a vacuum 3) One of the media is glass 4) The media I-II-III have indices of refraction that get bigger 5) Two of the media are the same I II III

nIIsinqII = nIIIsinqIII qII > qI  nI > nII nIsinqI = nIIsinqII nIIsinqII = nIIIsinqIII qII > qI  nI > nII qIII > qII  nII > nIII nI > nII > nIII I II III

Clicker Quiz Time Log in your remote! ACADEMIC HONESTY Each student is expected to hold himself/herself to a high standard of academic honesty. Under the UF academic honesty policy. Violations of this policy will be dealt with severely. There will be no warnings or exceptions. Log in your remote!

(air, diamond, ice) (diamond, ice, air) (diamond, air, ice) Q1 As a beam goes through layers of different materials (I, II, and III), it bends as shown in the figure. The angles in the figure indicate the angle between each beam and the vertical line. Those materials and their index of refraction are listed in the table. Identify each material (material I, material II, material III). (air, diamond, ice) (diamond, ice, air) (diamond, air, ice) (4) (air, ice, diamond) (5) (ice, air, diamond)

Lenses Converging lens Diverging lens

Glass lens (nG = 1.52) real, inverted image

Same shape lenses: the higher n, the shorter f The focal length of a lens is determined by the shape and material of the lens. Same shape lenses: the higher n, the shorter f Lenses with same n: the shorter radius of curvature, the shorter f Typical glass, n = 1.52 Polycarbonate, n = 1.59 (high index lens) Higher density plastic, n ≈ 1.7 (ultra-high index lens)

Clicker Quiz Time Log in your remote! ACADEMIC HONESTY Each student is expected to hold himself/herself to a high standard of academic honesty. Under the UF academic honesty policy. Violations of this policy will be dealt with severely. There will be no warnings or exceptions. Log in your remote!

Q2. A parallel beam of light is sent through an aquarium. If a convex lens is held in the water, it focuses the beam (…….. ……………………. ) than outside the water nair = 1, nwater = 1.33 closer to the lens (b) at the same position as (c) farther from the lens