Cue Column | Note Column
| Cue | Notes |
|---|---|
| What is Ray Optics? | Branch of physics treating light as straight-line rays. Covers reflection, refraction, TIR, lenses, mirrors, prisms, and optical instruments. |
| Mirror Formula | 1/v + 1/u = 1/f (PLUS between terms). u always negative. Concave: f < 0. Convex: f > 0. |
| Lens Formula | 1/v − 1/u = 1/f (MINUS between terms). u always negative. Convex: f > 0. Concave: f < 0. |
| Magnification Mirror | m = −v/u (has negative sign). m > 0 → erect. m < 0 → inverted. |
| Magnification Lens | m = (NO negative sign). Same sign convention applies for v and u. |
| TIR Conditions | (1) Denser → Rarer medium. (2) Angle > critical angle θ_c. BOTH required. |
| Power of Lens | P = 1/f (f in metres). Unit: Dioptre (D). Convex: P > 0. Concave: P < 0. |
| Snell's Law | sin θ_{1} = sin θ_{2} |
| f = R/2 | Focal length = half radius of curvature for spherical mirrors. |
| Prism Deviation | δ = (i + e) − A. Minimum when i = e. |
Summary
Ray optics governs how light travels, reflects, and refracts at surfaces. The two most critical formulas are the mirror and lens equations with correct Cartesian sign conventions. NEET awards 3–4 questions per year from this topic, almost always testing sign convention, magnification, image nature, and optical instruments.