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Proper high quality notes of class 12th NCERT. Every point from Scratch till advanced level useable fir Exams such as :- Boards , NEET , JEE , CET.
by @abhijeet
Ray optics is a branch of optics that models light as rays moving in straight lines, based on rectilinear propagation and the laws of reflection/refraction. Reflection occurs when light bounces back into the same medium; the angle of incidence equals angle of reflection, and incident ray, reflected ray and normal at point of incidence lie in the same plane. Spherical mirrors are sections of a hollow sphere, polished on one side: concave if bulging side polished, convex if inner hollow side polished. Key definitions: pole (midpoint of mirror), center of curvature (centre of original sphere), radius of curvature (distance from pole to centre), principal axis (line joining pole and centre), aperture (diameter), focus (point where parallel rays converge/ appear to diverge), focal length (pole to focus). Sign convention: distances measured from pole, along incident light direction positive, opposite negative; heights upward positive. For concave mirror focal length and radius negative; for convex positive. Relation f=R/2 derived using small aperture approximation. Image formation uses four rules: parallel ray passes through focus; ray through focus becomes parallel; ray through centre retraces; ray hitting pole reflects symmetrically. Concave mirror image cases: beyond C real inverted diminished between C and F; at C same size real inverted at C; between F and C real inverted magnified beyond C; at F image at infinity; between F and P virtual erect magnified behind mirror. Convex mirror always forms virtual erect diminished image behind mirror. Mirror formula 1/v+1/u=1/f holds for all spherical mirrors with proper signs; derived using similar triangles and small aperture assumptions. Linear magnification m = height of image / height of object = -v/u; positive m indicates virtual erect image, negative m real inverted; |m|>1 magnified, <1 diminished, =1 same size. Spherical aberration: marginal rays focus closer than paraxial rays causing blurred image in large aperture mirrors; corrected by reducing aperture, using stops, or parabolic mirrors. Uses: concave mirrors in shaving/makeup, head mirrors, reflectors; convex mirrors as rear-view and security mirrors.
# Ray Optics: Reflection and Spherical Mirrors ## Overview - Optics has two branches: Ray optics and Wave optics. - Ray optics treats light as rays travelling in straight lines (rectilinear propagation); it explains reflection, refraction, and image formation by lenses and mirrors. - Wave optics deals with wave nature: interference, diffraction, and polarisation. ## Reflection of Light > **Definition:** Reflection is the bouncing back of light into the same medium after striking a surface. - Incident ray, reflected ray, and normal at the point of incidence are used to describe reflection. - **Laws of reflection:** 1. $\angle i = \angle r$ 2. Incident ray, reflected ray, and normal at the point of incidence all lie in the same plane. - These laws hold for plane and spherical reflecting surfaces. ## Spherical Mirrors - Made by cutting a cap from a hollow glass sphere and polishing one side. - Two types: - **Concave mirror:** polished on the outer/bulging side; reflection occurs on the inner curved surface. - **Convex mirror:** polished on the inner hollow side; reflection occurs on the outer curved surface. … import to see the full notes, cards, quiz, glossary and exam questions.
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