Physics · Class 12 · Chapter 9
Ray Optics and Optical Instruments
11 lessons 107 min 4 simulations 9 practice questions
This chapter treats light as rays that travel in straight lines and follow the laws of reflection and refraction. Using NCERT's Cartesian sign convention it derives the mirror equation, refraction at a spherical surface, the lens maker's formula and the thin lens formula, then covers total internal reflection, lens combinations, refraction through a prism, and the working of the simple microscope, compound microscope and telescope.
What the exam asks
NEET asks image-formation numericals with mirrors and lenses, apparent depth, critical angle, lens maker's formula (including a lens dipped in a liquid), power of lens combinations, prism minimum deviation, and magnifying power of microscopes and telescopes. Most marks are lost to sign errors, to using the mirror formula for a lens or the reverse, and to using the wrong magnification formula for the adjustment asked.
Lessons
11 lessons · 107 min
1Reflection by spherical mirrors and the sign conventionNCERT § "Reflection of Light by Spherical Mirrors"7 min2The mirror equation and magnificationNCERT § "The Mirror Equation"11 min 1 sim3Refraction and apparent depthNCERT § "Refraction"7 min4Total internal reflectionNCERT § "Total Internal Reflection"11 min 1 sim5Refraction at a spherical surfaceNCERT § "Refraction at a Spherical Surface"7 min6Thin lenses: lens maker's formula and thin lens formulaNCERT § "Refraction by a Lens"12 min 1 sim7Power of a lens and combinations of thin lensesNCERT § "Power of a Lens"7 min8Refraction through a prismNCERT § "Refraction through a Prism"11 min 1 sim9Simple and compound microscopeNCERT § "The Microscope"7 min10TelescopeNCERT § "Telescope"7 min11Chapter reviewMust-know facts, traps and formulas20 min