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Introduction |
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when a ray of light travelling in one medium enters another medium of different optical density. |
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Refraction of Light |
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when a ray of light is incident on the boundary separating the two media having different densities. |
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Laws of Refraction |
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The incident ray, the refracted ray and the normal to the surface at the point of incidence all lie in one plane. |
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Refraction of Light through a Glass Slab |
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When a ray light is passing from air to glass, that is, from a rarer medium to a denser medium, the refracted ray bends towards the normal drawn at the point of incidence. |
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Verification of Laws of Refraction - An Alternate Method |
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The incident ray, the refracted ray and the normal to the surface at the point of incidence all lie in one plane. |
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Lenses |
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A lens is a portion of a transparent refracting medium bounded by two surfaces which are generally spherical or cylindrical or one curved and one plane surface. |
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Terminology Used in Optics |
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The focal length of a convex lens is always positive and that of a concave lens in always negative. |
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Formation of Image by a Convex Lens |
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When an object is placed in front of a lens, light rays coming from the object fall on the lens and get refracted. |
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Formation of Image by a Concave Lens |
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An incident ray of light coming from the object parallel to the principal axis of a concave lens after refraction appears to come from its focus. |
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Sign Convention for Lenses |
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The distances measured in the direction of incident rays are positive and all the distances measured in the direction opposite to that of the incident rays are negative. |
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Lens Formula |
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The values of the known parameters should be used with their proper sign as per the sign convention. |
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Magnification |
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As per sign convention for lenses, the height of an inverted and real image is negative and hence the magnification of a lens is negative when it produces an inverted and real image. |
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Power of a Lens |
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Whenever a ray of light passes through a lens (except when it passes through the optical centre) it bends. |
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Summary |
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The change of direction suffered by a ray of light as it passes obliquely from one medium to another is known as refraction. |
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Question and Answers |
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Multiple Choice Questions |
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