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Optics
Reflection, refraction, lenses, wave optics, diffraction
Key Concepts
- Reflection: angle of incidence = angle of reflection
- Snell's law: n₁ sinθ₁ = n₂ sinθ₂; TIR occurs when θ > critical angle
- Lens formula and mirror formula use same sign convention
- Young's double slit: interference pattern with bright and dark fringes
- Diffraction: bending of waves around obstacles; single slit produces central maximum
Important Formulae
| Mirror/lens formula | 1/f = 1/v − 1/u |
| Magnification (mirror) | m = −v/u |
| Snell's law | n₁ sinθ₁ = n₂ sinθ₂ |
| Critical angle | sin C = 1/n (n = refractive index) |
| Fringe width (YDSE) | β = λD/d |
| Lens maker's formula | 1/f = (n−1)(1/R₁ − 1/R₂) |
Quick Tips
- New Cartesian sign convention: distances measured from pole; along incident ray = positive.
- Power of lens P = 1/f (in metres); unit = dioptre. Lenses in contact: P = P₁ + P₂.
- In YDSE: path difference = nλ for bright fringe; (2n−1)λ/2 for dark fringe.
Practice Questions
Practice 20 randomly selected NEET questions on Optics. Answers are revealed after each question.
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