33 Facts about mirrors and images




1.     When a light ray travels from one medium to any another part of it is transmitted and part of it is reflected. The transmitted ray is refracted.
2.      Real images are formed at point where light ray actually intersect while virtual images formed when light only appear to intersect.
3.     Plane mirrors form virtual images while lens formed real images, virtual images do not exist.
4.     Magnification is the ratio of image height to object height or ratio of image distance to the object distance.
5.     If magnification is negative if the image is inverted or upside down.
6.     Images formed on plane mirrors are have left and right reversed, inverted, unmagnified and equidistance with object.
7.     Your dressing mirror is a 2nd surface mirror.
8.     Spherical mirrors are mirror whose surface shapes are spherical with radius of curvature r. Concave and convex mirror are the two types of mirrors. In concave mirror the reflecting surface bend inward while in convex the reflecting surface is bending outward.
9.     Focal point is places where light from an object appear intersect, for concave it is in front of the mirror while in convex it is behind the mirror.
10.                        Focal length is the distance between from the surface of a mirror to the focal point; it is half of the radius of curvature.
11.                        Radius of curvature is the radius the mirror will have if it were a complete sphere. It is always positive.
12.                        The mirror equation is given by i/f=1/do +1/di, where f is the focal length, do and di are the object and image distance respectively.
13.                        Apparent depth is due to the refraction of light
14.                        Lenses are  refract light to form image while mirror reflect light to form image.
15.                        The thin lens equation is same as mirror equation
16.                        In lens incident light rays converge  on the foal length.
17.                         The number of images formed by a plane mirror incident at an angle θ is given by (360/θ)-1 if θ is a multiple of 360 and if not the number of image is given by (360/θ) because the last two images will not overlap.
18.                        In concave mirror if the object is between the focal point  and the pole , the image formed is behind the mirror, virtual , erect and larger than the object.
19.                        In concave mirror, if object is at the focal point the image formed at infinity
20.                        In concave mirror is the object is between the focal point and the and centre of curvature ,  the image is real, inverted and larger than the object.
21.                        In concave mirror  if the object is at the centre of curvature , then the image formed is also the centre of curvature, real, inverted and unmagnified.
22.                        In concave mirror when  the object is beyond the centre of curvature of the mirror the image formed is diminished, inverted, real and between the focal point and the centre of curvature .
23.                         The image is at focal point , real, inverted and diminished  if the object is at infinity.
24.                        In convex mirror image formed is always erect, virtual, diminished and between the pole and focal point of the mirror no matter the position of the object.
25.                          Refracting telescope uses a combination of lenses to  form images.
26.                        Plane mirrors are used in periscope, kaleidoscope, reflecting galvanometer and as dressing mirror.
27.                        Spherical convex mirrors are used as  car driving mirrors, dentist mirror,  shaving mirrors, reflecting telescope etc.
28.                        Systems with shorter focal length have greater optical power than a system with longer focal length.
29.                        Longer focal length is used for photography and telecopy.
30.                        Shorter focal length is needed for microscopy, because substances are brought very close and very powerful focal power is needed.
31.                        Lenses maintain same focal length as light travel from front to back and from back to front.
32.                        A flat surface has its radius of curvature close equal to infinity.
33.                        Linear magnification is not always useful for magnifying power in lenses.

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