light ncert

• image formed by a plane mirror is always virtual and erect and laterally inverted
• pole IS part of the mirror
• centre of curvature is NOT a part of the mirror
• C lies in front of concave and behind convex (reflecting surfaces)
• PC = R
• principal axis is the normal to the mirrors at their poles
• if rays parallel and close to the principal axis are incident on a spherical mirror, after reflection, the pass or seem to come from a point on the principal axis. this point is called the principal focus
• diameter of reflecting surface of a spherical mirror is called the aperture
• aperture is smaller than R
• radius of curvature = 2f
• convex mirrors are preferred in rear view mirrors as they always give an erect (though diminished) image of an object, and they give a wider field of view as they are curved outwards, enabling the driver to see more of the road than possible with a plane mirror.