a branch of theoretical physics that studies the behavior of matter and energy at the atomic and subatomic level, where laws different from classical physics apply
Formula for photon energy: ε = h·ν — energy is proportional to frequency, where h — Planck's constant, ν — photon frequency
The energy of a single photon is directly proportional to its frequency ν. Planck (h) introduced the idea of the energy quantum: energy is emitted/absorbed in discrete portions.
Formula for photon energy: ε = h·c / λ — energy is inversely proportional to wavelength, where h — Planck's constant, c — speed of light, λ — wavelength
The shorter the wavelength, the higher the photon's energy. Used, for example, to calculate energy in the X-ray and ultraviolet ranges.
Formula for photon momentum: p = ε / c = h / λ — momentum is proportional to energy and inversely proportional to wavelength, where ε — photon energy, c — speed of light, h — Planck's constant, λ — wavelength
A photon possesses momentum despite having no rest mass. Momentum is important in calculations of light pressure and the photoelectric effect.
Formula for energy-mass equivalence: ε = m·c² — body's energy is proportional to its mass multiplied by the square of the speed of light
From Einstein's special theory of relativity: energy and mass are interchangeable. Even for photons, an equivalent mass can be calculated during motion.
Formula for photon mass: m = ε / c² = h / (λ·c) — mass is expressed through energy or through wavelength, Planck's constant, and speed of light
Although a photon has no rest mass, its energy allows for the calculation of an equivalent mass. This is applicable in some quantum and astrophysical models.
Formula for work function: A = h·ν₀ = h·c / λ₀ — minimum energy required to remove an electron from a substance, expressed through threshold frequency or wavelength
Work function **A** — minimum energy required to eject an electron from a surface. Depends on the material: each substance has its own threshold frequency ν0 or wavelength λ0.
Formula for photoelectric effect energy balance: h·ν = A + e·U₃ — photon energy is spent on electron work function and overcoming stopping potential
Photon energy goes into overcoming the work function **A** and imparting kinetic energy to the electron. **eU3** — energy corresponding to the stopping voltage required to halt photoelectrons.
Formula: h = 6.626 × 10⁻³⁴ J·s — fundamental physical constant, relating photon energy to its frequency
A constant relating the frequency of electromagnetic radiation to the energy of a photon. It is the basis of all quantum physics.
Formula: c = 3.00 × 10⁸ m/s — fundamental physical constant, defining the maximum speed of electromagnetic wave propagation in vacuum
The maximum speed of information transfer and photon movement in vacuum. Used in all formulas related to wavelength and energy.
Formula: e = 1.602 × 10⁻¹⁹ C — fundamental physical constant, characterizing the charge of a single electron or proton
The charge of a single electron or proton. Used in calculations of photoelectron energy through stopping voltage.