Study guides › C/P › Physics
Light & Optics
Light is an electromagnetic wave that reflects, refracts, focuses, diffracts, interferes, and polarizes. You will use Snell's law, draw and calculate images from mirrors and lenses with correct sign conventions, and analyze slit and polarizer setups.
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What this chapter covers
- Electromagnetic Waves & the Spectrum. Know the order of the spectrum, c = fλ, and E = hf. They connect optics, spectroscopy, and atomic physics.
- Reflection, Refraction & Total Internal Reflection. Snell's law and the critical-angle condition show up on almost every optics section, often with clean 30° and 60° angles.
- Mirrors & Ray Diagrams. Mirror questions are solved by one equation and three sign rules. Learn the conventions and never guess a sign.
- Thin Lenses, Power & the Eye. Lens problems reuse the mirror equation but with different sign meanings. Watch where the image forms relative to the object.
- Diffraction, Interference & Polarization. Slits and polarizers show that light is a wave. Expect fringe-spacing ratios and Malus's law with clean angles.
Key points to know
- All EM waves travel at c in vacuum and are transverse
- Order by increasing frequency: radio, micro, IR, visible, UV, X-ray, gamma
- Snell: n₁ sinθ₁ = n₂ sinθ₂, angles from the normal
- Higher n: slower light, bends toward the normal
- f = R/2; concave f > 0, convex f < 0
- 1/o + 1/i = 1/f; M = −i/o
- Same equation as mirrors; f > 0 converging, f < 0 diverging
- i > 0: real, opposite side of the lens from the object
Try a practice question
Which of these forms of electromagnetic radiation has photons of the highest energy?
- Radio waves
- Visible light
- Infrared
- Gamma rays
Show the answer
D. Photon energy E = hf rises with frequency. Gamma rays have the highest frequency and the shortest wavelength of the regions listed.
Common questions
What does this chapter cover?
Light & Optics covers Electromagnetic Waves & the Spectrum, Reflection, Refraction & Total Internal Reflection, Mirrors & Ray Diagrams, Thin Lenses, Power & the Eye, Diffraction, Interference & Polarization.
What should I know first?
All EM waves travel at c in vacuum and are transverse Order by increasing frequency: radio, micro, IR, visible, UV, X-ray, gamma Snell: n₁ sinθ₁ = n₂ sinθ₂, angles from the normal
25 original practice questions accompany this chapter in the app. Spaced review brings missed ideas back at the right time; it helps memory but cannot promise you will not miss an idea again.