Modern Physics: Relativity and Quantum Flashcards
Grade 11 · Science · Flashcards
Core vocabulary and formulas for special relativity, quantum mechanics, wave-particle duality, and atomic models.
Flashcards
- Special Relativity (First Postulate)
- The laws of physics are identical in all inertial (non-accelerating) reference frames.
- Special Relativity (Second Postulate)
- The speed of light in vacuum (c ≈ 3×10⁸ m/s) is the same for all observers regardless of source or observer motion.
- Time Dilation
- Δt = γΔt0; a moving clock runs slow relative to a stationary observer; γ ≥ 1.
- Length Contraction
- L = L0/γ; a moving object appears shorter along its direction of motion as measured by a stationary observer.
- Lorentz Factor (γ)
- γ = 1/√(1 - v²/c²); equals 1 at rest, increases toward infinity as v → c.
- Mass-Energy Equivalence
- E = mc²; the rest energy of a mass m; implies mass can be converted to energy and vice versa.
- Photon Energy
- E = hf = hc/λ; energy of a single photon depends on frequency (or inversely on wavelength).
- Photoelectric Effect
- Light above threshold frequency ejects electrons; max KE = hf - φ (φ = work function); proved light is quantized.
- Work Function (φ)
- Minimum energy needed to eject an electron from a metal surface; φ = hf0 where f0 is the threshold frequency.
- de Broglie Wavelength
- λ = h/p = h/(mv); the wavelength associated with a moving particle of momentum p.
- Heisenberg Uncertainty Principle
- ΔxΔp ≥ ℏ/2; fundamental quantum limit — position and momentum cannot both be precisely known simultaneously.
- Bohr Model Energy Levels
- Electron energies in hydrogen: E_n = -13.6 eV/n²; electrons emit or absorb photons when transitioning between levels.
- Wave-Particle Duality
- Quantum entities (light, electrons) exhibit both wave properties (interference, diffraction) and particle properties (discrete hits, photoelectric effect).
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