RAY OPTICS
Laws of reflection:- (a) Incident ray, reflected ray and normal lie in the same plane. (b) Angle of incidence = Angle of reflection.
2. Images formed by plane mirrors:
(a) Virtual and erect (b) unit magnification (c) distance of object and image from mirror are the same. (d) laterally inverted (e) If the object moves with a velocity ‘v’ then the velocity of image with respect to mirror or another stationary observer is ‘V’, but with respect to the object the velocity of image is 2v
No: of images: If q is the angle between the mirrors and if is even, then number of images N =
If is odd then if object is placed symmetrically N =
if object is place unsymmetrically n =
Rotation of mirror: If the mirror is rotated in its own plane, there is no change for incident ray, reflected ray and normal. If the mirror is rotated in the plane of incidence by an angle q, the incident ray remains fixed, normal rotates by q, reflected ray rotates by 2q.
SPHERICAL SURFACES:
Radius of curvature and focal length are related as r = 2f. Focal length of convex mirror is positive and concave is negative. If u is the onbject distance, V the image distance and f the focal length,

Magnification Areal magnification =
Sign convention: (1) All distances are measured from the pole . (2) Distances measured in the direction of incident ray are positive, while those in opposite direction to incident ray are negative.
(3) Hights above principal axis are positive and vice versa (4) Rays are plotted from left to right (5) Focal length of convex mirror is positive and that of concave mirror is negative (6) If the image is real, linear magnification is negative and if the image is virtual linear magnification is positive.
If X1 and X2 are distances of object and image from the focus of a concave mirror, then f =Ö x1x2
Focal length and radius of curvalue of a plane mirror are infinity. Power of a plane mirror is zero
REFRACTION
Laws of refraction: (a) incident ray, reflected ray and normal to the separation at the point of incidence lie in a plane
(b) 1m2 = (c) When a ray travels from one medium to another, wavelength and velocity change, but frequency
remains same
1m2 = = 1m2 =

wmg = m depends only on nature of media, colour of light (l) and temperature
Applications:
1. Object in a denser medium and observer in rarer medium d- real deapth
rmd = Shift =
2. Objct in a rarer medium and observer in denser medium
rmd = Shift = (m - 1)h h-real height