Name: Grade and Section: Score: School: Teacher: Subject: General Physics 2 LAS Writer: JEREMIAH S. SABRIDO Content Evaluator: EMMA T. SURITA MICHAEL DAVE NALAGON Lesson Topic: Reflection, Refraction, Dispersion, and Polarization Quarter 4 Wk. 3 LAS 2 Learning Targefls: Solve problems involving Reflection, Refraction, Dispersion, and Polarization in context such as, but not limited to sunglasses, atmospheric haloes, and rainbows. STEM-GP120PT-lVC-21 Reference(s): Semay and Faugn, J., 2006. Holt Physics. 10801 N. MoPac Expressway, Building 3, Austin, Texas 78?ng Holt, Rinehart and Winston, pp.451-500. Reflection, Refraction, Dispersion, and Polarization in Rainbow A rainbow is meteorogical phenomenon that is caused by reflection, refraction, and dispersion of light in water droplets resulting in a spectrum of light appearing in the sky. Reflection is when light bounces off an object. The ray that bounces back is called the reflected ray. Light entering a water droplet is refracted. It is then reflected back by the droplet. As this reflected light leaves the droplet, it is refracted again at multiple angles. Refraction is a result of a ray of light being slowed down or sped up as it passes from one medium to another. When light is passed through a glass prism, it splits into its spectrum of colours (violet, indigo, blue, green, yellow, orange, red} and this process of white light splitting into its constituent colours is termed as dispersion. Refraction is responsible for dispersion in rainbows. Light reflecting off a surface tends to be polarized. Light is electromagnetic radiation that consists of oscillating electric and magnetic fields with different wavelengths. The electric field oscillates in a direction that is perpendicular to the Iig ht ray's direction of travel, and the plane that the light ray and the electric vectorform is called its polarization. The polarization of rainbow is caused by the internal reflection. The rays strike back at the surface of the droplet close to the Brewster angle {polarization angle), so almost all the light reflected is polarized perpendicular to the incidence plane. Just how much the light of different frequencies is bent when entering the droplet is described by Snell's Law msin, = nrsinB, where n; = index of refraction of first medium, sins, = sine of the angle of incidence, n, = index of refraction of second medium, and sine, = sine of the angle of refraction. It's the different refraction angles for the different frequencies of light that gives a rainbow its colours. Refle 'on Refra ion We droplet Sunlight Z Dispersion Sample Problem 1: A beam of light going through a medium with an index of refraction of 1.14 has an angle of incidence of 48 with another medium. If the light wave Is at a new angle of 39. what is the index of refraction for the second medium? Sample Problem 2: A ray of light goes from air with an index of refraction of 1.0 to a drop of rain with an angle of incidence of 49. What is the angle of refraction of the color green of light? Refer to table 1 to get the indices of refraction at various wavelengths. Given: m: 1.14 sin; = 48 Sinr = 39" m: ? Given: Solution: . . _ sin 4-9 Flair: 1.0 msmi _ 5mg). 5mg!\" = (1'0\" 1.33;} sine, = 49 11,. _ sine, : ? _ nisini sins, = 0.56 or 0.57 _ 51113,. = mum, - 1.335 Tl?- Solution: ' ' sin 43 nismii = rst 9r n, = (1.14)(sm39a;} sinr 5i 9,- n,sm9, m = 1.346 "r = smearr ACTIVITY: Solve the following problem. Referto table 1 to get the indices of refraction at various wavelengths (colors). Show your solutions. Table 1. Index of Reection n In Selected Media at Various Wavelengths Medium Red [660 urn} Orange {610 nm} Yellow {580 rim} Green [550 nm] Blue [4'10 rim} \\flolet [410 nm) Water 1.331 1.332 1.333 1.335 1.338 1.342 Diamond 2.410 2.415 2.417 2.426 2.444 2.458 Glass, Crown 1512 1.514 1.518 1.519 1.524 1.530 Glass, Flint 1.662 1.665 1.66? 1.674 1.684 1.698 Polystyrene 1.488 1.490 1.492 1.493 1.499 1.506 Qua i'tZ, fused 1.455 1.455 1.458 1.459 1.452 1.468 The combined effects of reflection, refraction, and dispersion can produce beautiful rainbows from a sprinkler. Tiny drops of water act like a prism, splitting light into individual colours depending on their wavelength. If a beam of light from air goes through a water droplet with an angle of incidence of 51, what would be the refractive angle of these dispersed colours: Blue, Orange, Yellow