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Refraction. Bending of light when it passes from one medium to another Refraction occurs because the speed of light depends on the material through which it passes Index of refraction = ratio of the speed of light in vacuum to its speed in the material.
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Refraction • Bending of light when it passes from one medium to another • Refraction occurs because the speed of light depends on the material through which it passes • Index of refraction = ratio of the speed of light in vacuum to its speed in the material
Refraction of a meter stick upon entering water. • Snell's law: n1 sin q1 = n2 sin q2 n = refractive index q = normal angle Wavefronts in Air... Water
Refraction in a piece of glass • If two surfaces of the glass are parallel, the emerging wave is parallel to incident wave • Otherwise the emerging wave and incident wave have different directions
Dispersion • Dispersion occurs because the index of refraction depends on wavelength • Violet light is bent most • Red light is bent least
Making an image with a TELESCOPE Aperture Aperture Image
Making spectra with a SPECTROSCOPE Aperture Aperture Image Dispersion
Making an image with a TELESCOPE SLIT SLIT Image
Making spectra with a SPECTROSCOPE SLIT SLIT Image Dispersion
Spectral resolution: SLIT SLIT Image Dispersion