Geometric optics, also known as ray optics, is a branch of optics that describes light propagation in terms of rays. These rays are straight lines that represent the path along which light energy travels. Geometric optics is based on the assumption that light travels in straight lines and focuses on the behavior of light when it interacts with objects such as lenses, mirrors, and prisms.
Key concepts in geometric optics include:
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Reflection: The bouncing of light rays off surfaces. According to the law of reflection, the angle of incidence (the angle between the incoming ray and the normal to the surface) is equal to the angle of reflection (the angle between the reflected ray and the normal).
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Refraction: The bending of light rays as they pass from one medium to another, which occurs due to a change in the speed of light in different media. Snell's law quantifies this phenomenon.
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Lenses: Optical devices made of transparent materials that bend light rays. Convex lenses converge light rays, while concave lenses diverge them. The focal point is a key concept associated with lenses.
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Mirrors: Reflective surfaces that can focus or disperse light rays. Convex mirrors produce virtual images, while concave mirrors can produce real or virtual images depending on the object's position relative to the focal point.
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Optical Instruments: Devices such as telescopes, microscopes, and cameras that utilize principles of geometric optics to magnify or focus images.
Geometric optics is particularly effective in describing phenomena when light behaves as a series of rays, typically in situations where the dimensions of optical elements are much larger than the wavelength of light. However, it is less accurate in situations involving diffraction and interference, where wave optics or physical optics is more appropriate.
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