17.1 quantum physics - david liao ap physics 2/17.1... · quantum physics (for ap physics 2) page 1...
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Quantum physics (for AP Physics 2)
Page 1 of 3 DAVID LIAO.COM
Wave-particle duality (for punctuated isolation scenarios)
wavefunction – represents vibration across space particle – concept of point-like object used for book-
keeping of possible future point-like interactions
∆Prob |𝜓 𝑥 | ∆𝑥
Light
Wave characteristics
𝑐 𝜆𝑓
𝑐 3.00 10ms
Particle characteristics
𝐸 ℎ𝑓
𝑝𝐸
𝑐ℎ𝜆
ℎ 6.626 10 J ⋅ s
Photoelectric effect
ℎ𝑓 𝜙 𝐾
Quantum physics (for AP Physics 2)
Page 2 of 3 DAVID LIAO.COM
Wave-particle duality (for punctuated isolation scenarios)
wavefunction – represents vibration across space particle – concept of point-like object used for book-
keeping of possible future point-like interactions
∆Prob |𝜓 𝑥 | ∆𝑥
Matter
Particle characteristics
Wave characteristics
de Broglie hypothesis
Guess: Relationships between wave and mechanical features for light hold for matter.
𝜆ℎ𝑝
𝑓𝐸ℎ
Particle diffraction
Using the de Broglie wavelength leads to correct predictions of diffraction patterns.
Particles that are confined have quantized energies
Standing waves in physical media
Spatial confinement leads to standing waves at discretely separated frequencies.
Standing probability amplitude waves
Spatial confinement leads to standing wavefunctions with discretely separated frequencies, and, thus, discretely separated energies.
Bohr orbits
𝑐 2𝜋𝑟 𝑛𝜆 𝑛 1,2,3, …
𝑅 0.0529 nm𝑛𝑍
𝐸 13.6 eV𝑍𝑛
Quantum physics (for AP Physics 2)
Page 3 of 3 DAVID LIAO.COM
Light and matter exchange energy
The colors of light absorbed and emitted by gas can be computed by conceptualizing light in terms of particles while also conceptualizing electrons in terms of probability amplitude waves.
ℎ𝑓 𝑈 , ℎ𝑓 𝑈 ,
Emission spectra Absorption spectra