![]() Reflecting glass prism whose angles ( 45°, 45°, 90° ), It can change the path of light beam by 90° or 180°, So, it is used in some optical instruments such as periscope in submarines and binocular in the field. Communication as light can carry millions of electric signals in optical fiber cables.They are widely used nowadays in medical examination such as medical endoscope, which is used in diagnoses and operative surgery using laser beam.Transmitting lightin non-straight paths without much losses in the light intensity.Transferring lightto parts hard to reach.Optical fiberis a thread like tube of transparent elastic material in which the light ray enters from one end and undergoes successive multiple reflections until it emerges from the other end. When a light ray falls on any part of the internal wall of the optical fiber with an angle of incidence greater than the critical angle, it undergoes successive multiple reflections until it emerges from the other end without much losses in the intensity of light despite of the bending of the fiber. Optical fiber is a thread-like tube of transparent elastic material, which can be bent while containing lightand can be made of a bundle of fibers. Applications on the total reflection of light Where ( n ) is the absolute refractive index of the optically higher dense medium. ĭeduction of the relation between the sine of the critical angle & the refractive index of a medium The angle of incidence must exceed the critical angle between the two media. ![]() The light rays travels from the optically higher dense medium to the optically less dense one.Optical fibres Conditions of the total reflection When the critical angle of a medium with air = 40°, This means that the angle of incidence in this medium = 40°, corresponds an angle of refraction in air = 90°. Total reflection is the reflection of the light rays in the optically higher dense medium when the angle of incidence exceeds the critical angle of the optically higher dense medium. Ĭritical angle between two media ( Φ c ) is the angle of incidence in the optically higher dense medium, which corresponds to an angle of reflection in the less dense medium equals 90°. When the angle of incidence exceeds the value of the critical angle, the light ray does not emerge to the optically less dense medium but reflects totally in the optically higher dense medium and this phenomenon is called total reflection. Īt a certain angle of incidence, the angle of refraction reaches its maximum value, which is 90° and the lightemerges tangent to the separating surface and is called in thi s case grazing ray, the angle of incidence is called the critical angle ( Φ c ). Light refraction is used in explaini ng total reflection and dispersion of white light, When a light ray travels from an optically higher dense medium ( such as water) to an optically less dense one ( such as air ), it refracts away from the normal line, As the angle of incidence increases in the optically higher dense medium, the angle of refractionincreases in the optically less dense one.
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