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Light - Reflection & Refraction
High trendapprox. 7 marksSections C/D — ray diagrams, mirror/lens formula numericals and image-property tables.
CBSE 2027 — dates, rules and official papers →Ask the tutor1Mark every ray with an arrowhead and label F, C / 2F clearly — unlabelled diagrams lose the diagram mark.
Notesformulae · proofs · mind-map — one view
Learn the 9 conceptsteach yourself first, then practise each
Reflection of Light1–4 marks Visual
Apply the laws of reflection and state the image a plane mirror forms — virtual, erect, same size, as far behind as the object is in front.
Mirror formula 1/v + 1/u = 1/f and magnification m = −v/u2–3 marks Visual
Solve image-position numericals for spherical mirrors.
Lens formula 1/v − 1/u = 1/f and m = v/u2–3 marks Visual
Solve image-position numericals for thin lenses.
Sign convention (New Cartesian)1–2 marks
Decide signs of u, v, f, h before substituting.
Ray diagrams (concave/convex mirror & lens)3–5 marks Visual
Use two of the standard rays through F or C / 2F to locate the image.
Refraction of light and the laws of refraction (Snell's law: sin i / sin r = constant)2–3 marks Visual
State the two laws and predict the bend — towards the normal into a denser medium, away from it into a rarer one.
Refractive index n = c/v (absolute) and n₂₁ = v₁/v₂ (relative)1–3 marks
Compare optical densities and compute the speed of light in a medium.
Power of a lens P = 1/f (dioptre); lenses in contact P = P₁ + P₂1–2 marks
Convert f in metres to dioptres with the right sign, and add powers for lenses in contact.
Applications of spherical mirrors and lenses (headlights, solar furnace — concave; rear-view mirror — convex; magnifier and spectacle lenses)1–2 marks Visual
Name the mirror or lens used in a situation and give the one-line reason.
When you’re ready — practise or test the whole topic