physicsexam3

# physicsexam3 - Chapter 24 - ray optics (also called...

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Chapter 24 - ray optics (also called geometrical optics) - in the ray optics approximation, light travels along straight lines called rays. These rays change direction when light is reflected or refracted. Ray optics gives an accurate description of light propagation when light passes through openings or strikes objects that are large compared to its wavelength. - reflection and refraction ( see pictures in notebook ) - for reflection and refraction, we measure the direction of a ray using the angle θ made by the ray with the direction normal (perpendicular) to the surface of interest. According to the law of reflection, the angle of incidence is equal to the angle of reflection: θ I = θ r . Refraction is described by Snell’s law, n 1 sin θ 1 = n 2 sin θ 2 where the index of refraction n=c/v is the ration of the speed of light in a vacuum (c) to the speed of light in the refracting material (v). By applying the law of reflection and Snell’s law, we can calculate how light interacts with plane mirrors, curved mirrors, lenses, and other refracting objects such as flat plates and water droplets. - ray tracing ( see pictures in notebook and book) - ray tracing is the process of using light rays that emanate from an object to derive the location and other properties of an image. Important properties of an image include the following: - real image: light from the object passes through the image point - virtual image: light rays do not pass through the image point. The image point is found by extrapolating rays back to a common point behind a mirror or in front of a lens - upright image: the image has the same orientation as the object - inverted image: the image is upside down compared with the object - enlarged image: the image is larger than the object (the magnification is |m| > 1) - reduced image: the image is smaller than the object (|m| < 1) - magnification: the ratio of the image height h i to the object height h o - m = h i /h o - according to our sign conventions for h 1 and h 0 , the magnification can be either positive or negative (see pages 813-14 and 820) - mirror equation: relates the object distance, the image distance, and the focal length for a curved mirror - 1/s o + 1/s i = 1/f - for a concave spherical mirror, f is given by: f=R/2 where R is the radius of curvature. For a convex spherical mirror, f has the same magnitude, but is

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## This note was uploaded on 02/29/2012 for the course PHYSICS 104 taught by Professor Dasu/karle during the Fall '11 term at Wisconsin.

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physicsexam3 - Chapter 24 - ray optics (also called...

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