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Interference of Light. Refraction (a review). Character of the wave in different (transparent) media wave travels slower Index of refraction n = c/v frequency is constant (wavelength changes) Law of Refraction (Snell’s Law) n 1 sin q 1 = n 2 sin q 2. Huygens Principle.
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Refraction (a review) • Character of the wave in different (transparent) media • wave travels slower • Index of refraction n = c/v • frequency is constant (wavelength changes) • Law of Refraction (Snell’s Law)n1 sin q1 = n2 sin q2
Huygens Principle • Propagation of plane wave by Huygen’s principle
Snell’s Law • Refraction • Similar triangles
Young’s Double Slit 1801 • Conditions for interference
Young’s Double Slit Constructive interference phase difference to be an integral number of wavelengths
Destructive Interference Condition Destructive interference (minima)
Young’s Double Slit Intensity behavior
Young’s Double Slit Intensity behavior algebraic approach
Young’s Double Slit Intensity behavior averaged over one period
Interference upon Reflection • Thin Film • in air • coatings
Phase changes upon Reflection Dense to less dense n1 > n2 Less dense to more dense n1 < n2
Thin Film in Air (Soap Film) • Near normal incidence • Conditions for reflected light interference Assume Condition for there to be constructive interference