A. Manalaysay – PHY2054, Fall 2004 CHAPTER 22 This chapter is all about reflection and refraction… but more about refraction. In a medium (such as glass, water, ice, etc.), light travels slower than it does in a vacuum. This is because the atoms and/or molecules that make up the medium act as obstacles; the light bounces of some, gets absorbed and re-emitted by others, and in the end it slows the light down. So, each medium has associated with it something we call the index of refraction:----> Index of refraction (just a ratio) The speed is different in different media, but the frequency stays the same, so the wavelength changes. This should be obvious if you consider that the speed of a wave (any wave) is equal to its frequency multiplied by its wavelength. Whenever light crosses an interface between two different media, it gets bent. The amount that it gets bent depends on the indices of refraction of the two media:---> Snell’s Law
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