Reflection of Light by Spherical Mirrors | Physics
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The document discusses spherical mirrors, including concave and convex types, their reflecting surfaces, and various applications such as in dental mirrors and rear view mirrors. It explains the laws of reflection, total internal reflection, and provides formulas for mirror equations and magnification. The conclusion states that concave mirrors can form real or virtual images depending on object placement, while convex mirrors always form virtual images.
Reflection of Light by Spherical Mirrors | Physics
- 1. Reflection Of light by spherical mirrors
- 2. Spherical mirrors Spherical mirror: Consider a glass with a hollow sphere and a reflecting surface. This reflecting hollow surface of sphere of which either sides are polished, forms the spherical mirrors. Spherical mirrors are of two types: Concave mirror and b) convex mirror. The inward curved reflecting surface of the spherical mirror is known as concave mirror and the outward curved reflecting surface of the same spherical mirror is known a convex mirror.
- 3. Uses of concave and convex mirrors Concave mirrors: •Used as shaving and makeup mirrors •Used as reflectors in search lights, projectors etc • Used as mirrors by dentists •Used in reflecting telescope Convex mirrors: • Used as rear view mirror •Used as shaving and makeup mirrors •Used as safety viewers at dangerous corners
- 4. Laws of reflection The angle between the incident ray and normal i.e. angle of incidence is always equal to the angle between normal and reflected ray i.e. angle of reflection The ray which is incident on the surface, the normal and the ray which is reflected back lies on the same plane.
- 5. Total Internal Reflection • Total internal reflection: when a light travels from denser to rarer medium then it gets refracted away from the normal. As the angle of incidence is increased, the angle of refraction also increases. A point comes when the angle of refraction is 90˚ and there is no further refraction . At this point, the incident light gets totally reflected. This reflection is known as Total internal reflection .
- 6. Sign convention (a) When the light is travelling parallel to the principal axis, then the reflected ray is supposed to pass through the focus of the mirror (b) When the light travels through the centre of curvature, then it reflects back and traces its original path that it travelled. (c) When the light travels through the focus of the mirror, then the reflected rays travels parallel to the principal axis. It may be noted that these principles abide by the laws of reflection i.e. the angle formed by the incident ray is equal to that angle formed by the reflected ray.
- 7. Mirror equation and magnification formula: Mirror Equation: 1/f = 1/v + 1/u Magnification formula (m) = -(v/u) The mirror equation helps us to calculate the distance , location and nature of the image formed at the mirror. The magnification formula helps us to see if the image formed is magnified or diminished. The mirror equation is derived using the standard sign convention and in true for all cases
- 8. Conclusion The formation of a image in concave mirror can be real or virtual depending on the location and position of the object placed away from the mirror. However, in case of convex mirror , the image formed is always virtual. The formation of image, be it in concave or convex mirror always abides by the law of reflection.
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