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the change of direction of a ray of light as it passes obliquely from one medium into

the change of direction of a ray of light as it passes obliquely from one medium into another of different transmission speed. When light travels from a less dense to more dense medium ( light slows down ), the ray is refracted toward the normal .

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the change of direction of a ray of light as it passes obliquely from one medium into

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  1. the change of direction of a ray of light as it passes obliquely from one medium into another of different transmission speed

  2. When light travels from a less dense to more dense medium (light slows down), the ray is refractedtoward the normal. Example: light slows down when it passes from air into water n i i > r air water r

  3. When light travels from a more dense medium to a less dense medium (light speeds up), the ray is refracted away from the normal. Example:light speeds up when passing from glass into air air i n r glass i r <

  4. An object’s ability to decrease the speed of light, and therefore cause refraction, is given by its index of refraction. By definition: the index of refraction of any transparent substance is equal to the speed of light in a vacuum divided by the speed of light in that substance. n = c/v n = (3 x 108 m/s)/v

  5. The angles of incidence and refraction are related in such a way that n = (sin i)/(sin r), where i = angle of incidence and r = angle of refraction whenever light passes from a vacuum into the substance. In general, for light passing from medium 1 into medium 2, n1 sin q1 = n2 sin q2 This relationship is known as Snell’s Law. q1 n1 n2 q2

  6. Total Internal Reflectionmay occur when light enters a new medium and speeds up (bends away from the normal). Investigate here. The maximum angle of incidence in which light may enter air from another substance and not undergo total internal refraction is known as the critical angle, and is related to the index of refraction of the substance by: sin qc = 1/n

  7. Click here, here, and here to view simulations of Snell’s Law. View an analytical derivation of the geometrical relationship here. Investigate total internal reflection here.

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