Physics 012 1st Edition Lecture 25 Outline of Last Lecture I. Total Internal Reflectiona. As θ1 increases, θ2 also increases.b. At the critical angle, refracted light will follow the surface between the two media (θrefracted = 90 degrees).c. Any angle of incidence greater than the critical angle will result in total internal reflection (all light reflected, none entering second medium).i. Only happens when light beam goes from higher index of refraction to lower index of refraction (n1 > n2).ii. θc = sin-1(n2/n1)d. Problem: A beam of light is incident on the circular face of a glass cylinder at an angle of θ1. Find the maximum value of θ1 to get total internal reflection in the glass cylinder.i. θ1 will be at max value for T.I.R. when θ3 is at critical angle.ii. ngsinθ3 = nasin(90) = naiii. θc = θ3 = sin-1(na/ng) = 47.3 degreesiv. θ2 = 90 – θ3 = 42.6 degreesv. nasinθ1 = ngsinθ1vi. θ1 = sin-1([ngsinθ2]/na) = 67.1 degreesIII. Brewster’s Angle: angle at which light becomes completely polarized parallel to the reflecting surface (electric field will oscillate parallel to reflecting surface).These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.a. At this angle, the reflected ray and refracted ray will be perpendicular.b. tanθB = n2/n1IV. Dispersiona. The index of refraction for a given material varies slightly with wave length of light passing through that material. The index of refraction increases with smallerwavelengths.b. Ex. Glass Prismi. Different colored light within white light will have different angles of refraction, causing colors to be separated when exiting prism.V. Thin LensesOutline of Current Lecture VI. Diverging Lensa. Equation for magnification same as for mirrors.i. m = hi/ho = -di/dob. Lens equation same as mirror equation.i. 1/f = 1/do + 1/dic. Real images are on opposite side of lens as object, virtual images are on the same side of lens as object.d. Object placed between F (focal point) and 2F (twice focal length from center) creates a real image of increased size.e. Object placed further than 2F form center of lens creates a real image of reducedsize.f. Object placed within focal length creates a virtual image larger than object.VII. Converging Lensa. Equation for magnification same as for mirrors.i. m = hi/ho = -di/dob. Lens equation same as mirror equation.i. 1/f = 1/do + 1/dic. Focal length is always negative (like with a convex mirror).d. Image will always be virtual.VIII. Lenses in Combinationa. First lens is treated like object for second lens.b. Only final image can be seen (not image formed after first lens).c. Total magnification can be found by multiplying all individual magnifications.i. mtotal =
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