Presentation on theme: "IV. Optics Nature of light. Spectrum of electromagnetic waves."— Presentation transcript:
1 IV. Optics Nature of light. Spectrum of electromagnetic waves. Wavelength decreases Frequency increases Note: 1 nanometer = 10-9 meter
2 A. Geometric optics 1. Wave front and rays 2. Reflection wave fronts1. Wave front and raysnormal tosurface2. Reflectioninoutdiffuse reflection3. Refraction: Snell’s Lawindex of refraction:Example:n1n2n3
6 Example: A ray of light is incident in air on a block of a transparent solid whose index of refraction is n. If n =1.38, what is the largest angle θ1 for which total internal reflection will occur at the vertical face (point A)?An=1.38Example:ααn=1.52α
7 4a. Applications of total internal reflection 1) Binoculars often use total internal reflection; this gives true 100% reflection, which even the best mirror cannot do.2) Fiber optics.Light will be transmitted along the fiber even if it is not straightAn image can be formed using multiple small fibersThe typical value of the index of refraction for optical fibers:for the core n=1.48for the cladding n=1.46
8 5. Plane mirrordodiOOdodiIIdo = diho = hiImage in plane mirror:virtualerectthe same size6. Comments about objects and images created by different optical instruments: curved mirrors, lenses and their combinationsImage:real or virtualerect or invertedlager, smaller, or the same size as the object
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